Depicting Klingons
The depiction of the Klingon species, the iconic aggressive warrior race from the planet Qo'noS, has evolved throughout the years from a simple analogy of the American fear of Cold War-era Russians to a depiction of a complex and proud tradition-bound people who value honor as well as combat prestige. As Klingons became more and more popular, attention was placed into evolving the make-up effects, into establishing a unique Klingonese language and into exploring the ever more complex history, society, politics, culture, psychology and religion of the Klingon species.

First televised appearances 

Klingons were introduced in , making their first appearance in the season one episode . They were originally meant to be involved in only that installment. () The episode's writer, Gene Coon, was the person who initially imagined the species and their culture. However, both aspects were among multiple elements of the series which Star Trek Producer Gene Roddenberry joked originated from his "cousin in Ohio." (Inside Star Trek: The Real Story, paperback ed., p. 136)

Gene Coon primarily modeled the Klingons, metaphorically, on contemporary Russians, making the standoff between the species and the Federation representative of that between the Russians and the Americans during the then-ongoing Cold War. (Star Trek: The Original Series 365, p. 139) This view of the Klingons had their sociology theoretically aimed at "the collective good" rather than "individuality," as pointed out by Kor actor John Colicos. () The Klingon Empire was also a metaphor for Communist China and its allies in the Vietnam War, namely North Vietnam and North Korea. (These Are the Voyages: TOS Season One) David A. McIntee explained, "There is some suggestion that the Klingons represent a Cold Warrior's view of China in the 1960s – swarthy, brutally repressive." () Dave Rossi agreed, "In many ways, the Klingons were born out of our fear, as Americans, of [...] the Communists." ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray) According to D.C. Fontana, there were a range of other real-world sources that additionally gave rise to Coon's creation of the Klingons. "What did he want to accomplish? I think he just wanted a good, tough villain... for Kirk," Fontana speculated. "And I think he was basing a lot of it on the kind of attitude of the Japanese in World War II, the Nazis in World War II, because Gene was a World War II veteran marine and he really took all this to heart. And as a result, he modeled them on the worst villains he knew." ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray) McIntee concurred, "The Klingons with their conquests and military structure echo the Axis forces of World War Two as much as the Communist powers in Vietnam." () Chekov actor Walter Koenig specified, "They [the Klingons] were evil and nationalistic. But Star Trek did not address the baser things in man. There was no imperialism or colonialism. We addressed this obliquely, hoping that someone would pick up our message out there." (Cinefantastique, Vol. 27, No. 11/12, p. 61) 

After Gene Coon conceived the Klingons, a name for the species did not immediately come to mind. He took inspiration from a name which came into earshot, that of Lieutenant Wilbur Clingan – a friend of Gene Roddenberry who served with him in the Los Angeles Police Department. (Star Trek: The Original Series 365, p. 141; Star Trek Creator: The Authorized Biography of Gene Roddenberry, p. 131) Even when retired years later, Clingan was still proud to introduce himself as the first Klingon. Commented Robert Justman, "The question remains whether Gene named these creatures out of homage or revenge. I've heard it both ways." () Also under dispute is the nature of the production staff's reception to the name. According to the book Star Trek: The Original Series 365 (p. 141), the series' production staff liked how the moniker sounded, which led to Coon altering the spelling and using it for the fictional species. However, D.C. Fontana stated, "We never liked the name. We said, 'Gene, can't you come up with a different name than Klingon? We hate it.' It was odd-sounding. You know, Kling-on – as in clinging." (These Are the Voyages: TOS Season One) The detractors of the name were apparently unable to come up with a better one, and there wasn't enough time to settle on something else, so they left the name as it was. (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 40; These Are the Voyages: TOS Season One)

The script of "Errand of Mercy" introduces the Klingon look by saying, "We see the Klingons are Orientals," thereafter repeatedly describing them as "hard-faced, uniformed, heavily armed, wearing what looks like vests of mail (see the material used as mail by the Romulans.)" Indeed, the Klingons originally appeared as fairly ordinary Humans with heavy makeup as well as emboldened eyebrows, with some of the males having mustaches and goatees. The reason the Klingons were accepted as looking so Human-like, delineated from Humans mainly by their mannerisms and characters, was that the series had neither the materials, budget nor time necessary to create elaborate makeup for the Klingons. ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray)

The introduction of the Klingons in "Errand of Mercy" caused the casting of that episode to become a longer and more involved process than normal. This was because the production staff had little idea what a Klingon should look like. "I had never heard of a Klingon before," related Makeup Designer Fred Phillips. "And nothing in the script that I read told me what it was." (These Are the Voyages: TOS Season One) Because John Colicos had likewise never previously heard of Klingons, he was also initially uncertain how they should be. "My first thought was 'What the hell is a Klingon? What does a Klingon look like? Well, they'll know what it's all about." ("The Sword of Colicos", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) Colicos assumed the Star Trek makeup department, in particular, would know precisely how a Klingon should look. "When I arrived at Paramount," the actor continued, "the make-up man said to me, 'What in the hell does a Klingon look like?" () Recalling his own response, Colicos related, "I said, 'You don't know either?" (Cinefantastique, Vol. 28, No. 4/5, p. 59)

John Colicos and the relevant makeup artist sat down and began to devise how the Klingons should look. (Cinefantastique, Vol. 28, No. 4/5, p. 59) That makeup worker, Fred Phillips, started the process of designing the species by directly asking Colicos how he wanted to look. Despite thinking of the Klingons as the futuristic Russians they were intended to be, Colicos took inspiration from Genghis Khan, as Kor was likewise an ambitious military commander. (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 40) "He thought that was a hell of a good idea," Colicos said, regarding Phillips' reaction. () Colicos' hair happened to be very short and combed forward. He asked for it to be sprayed and slightly "kinked up." Due to the Genghis Khan influence, Colicos then proposed "a vaguely Asian, Tartar appearance," with an alien-looking "brown-green makeup."  (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 40) Colicos also took inspiration from Fu Manchu as an influence on his look as Kor. He instructed the makeup department, "Spray my hair black, give me a kind of swamp creature green olivey mud reptilian make-up, and we'll borrow some stuff from Fu Manchu, and put a long moustache and eyebrows on me." ("The Sword of Colicos", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) The makeup scheme was therefore actually a combination of a wide variety of sources, Colicos advising the makeup team, "Make me a little touch of Fu Man Chu [sic], and a little touch of Slavic Russian, and a little touch of everything." (Cinefantastique, Vol. 28, No. 4/5, p. 59) He later remembered, "Within two hours, this thing emerged and that was it." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 40)

John Colicos was pleased with how he had influenced the layout of the Klingon makeup. "I thought I was pretty crafty [...] because it only took 20 minutes to put on," he said. () Thus, Colicos set a precedent for all other members of the species. He concluded, "Everybody else after me took that as the prototype of the Klingons." ("The Sword of Colicos", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) Even the early conception of Klingons as ferocious conquerors was cemented largely by the initial portrayal of Kor. ()

The swarthy appearance of the Klingon faces was actually created with a dark brown cream base, which was applied to the actors' faces. (Star Trek: Aliens & Artifacts, p. 42) Rick Stratton, who was part of a small team of young makeup artists enlisted by Fred Phillips to work with him on , uncertainly recollected, "I think the makeup was called 'Mexican #1 or #2.' That was the name of the original makeup foundation – they actually had kind of racist names at the time, like 'Negro #1' and 'Mexican #2' – which was the basis for the original Star Trek makeups." ()

The males' facial hair appliances were lace, glued on using spirit gum, and their eyebrows were made to look bushy. (Star Trek: Aliens & Artifacts, p. 42) Noted Michael Westmore, "They actually shaped and penciled in the eyebrows with pencil." () Due to the minimalism of the makeup used, the Klingons were easy to create, from a makeup standpoint, and were therefore able to be shown in groups. (Star Trek: Aliens & Artifacts, p. 42)

The first time any Klingons were filmed was on Friday . () However, several minor changes were made between how the Klingons were initially planned to be portrayed in "Errand of Mercy" and how they ended up being shown in that installment. For example, a pair of Klingons guarding a munitions dump were scripted to have a couple lines of dialogue, though they don't speak in the episode's final version.  Also, two mere moments which acted as the set-up and payoff of a "stare-off" gag were shot but deleted from "Errand of Mercy". The gag involved, at one point, a Klingon shooting a hard stare at Kirk in a courtyard on Organia and – on another occasion, at the doors to Kor's office on the planet – another Klingon soldier receiving the same kind of look from Kirk. ()

As the makeup procedures for the Romulans were too costly for that species to be featured on a regular basis (despite the Romulans having been meant as an ongoing villain), the Klingons – much cheaper to create – replaced them as the show's chief antagonists. (Star Trek: Aliens & Artifacts, p. 42) "In the original series, all they wore was a dark face and their black hair," Michael Westmore observed. "Also, they didn't have the degree of facial hair that we had on them." ("Michael Westmore's Aliens: Season Two", DS9 Season 2 DVD special features) Although the creative staff hadn't intended for the Klingons to be recurring villains and never thought they would be as successful as they were, these expectations were changed by the fact they were considerably easy to do, basically requiring merely facial hair and slightly darkened skin. ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray; These Are the Voyages: TOS Season One) "Once we figured that out," reflected D.C. Fontana, "the Klingons became regulars." ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray) "It didn't happen at first, but they were good villains," offered Robert Justman. "A lot of these things didn't enter my consciousness at the time, but looking back on it now, I can see how unerring Gene [Coon]'s instincts were." () In agreement, Fontana described the ease at which the Klingons could be done as "the beauty of them." () She said further, "They became a very good adversary, because once you established them, you had to find out ways to explore them." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 40)

After "Errand of Mercy" 
The first installment in which the Klingons reappeared, the season 2 outing , at first hardly involved the species. Although D.C. Fontana wrote multiple drafts of the episode (between January 1967 and April of the same year), her version of the story featured no Klingons on Capella IV, where most of the episode's events take place. In fact, other than a subplot featuring a Klingon ship – which Fontana added at Gene Roddenberry's request – the Klingons were discussed but not seen in Fontana's form of the plot. It wasn't until Roddenberry did a rewrite of the episode's script (in May 1967) that the Klingons factored more heavily into the installment. Even though Gene Coon had created the species, Robert Justman included – among comments he sent Coon about the changes Roddenberry had made – the reminder, "We are not at war with the Klingon Empire in this show." (These Are the Voyages: TOS Season Two)

In the review of the  script for , de Forest Research referred to the "Now firmly established" Klingon Empire "as interstellar ."

David Gerrold proposed reusing Klingons in the second season episode , which was at that time a story entitled "A Fuzzy Thing Happened To Me...". The suggestion, later described by Gerrold as "almost accidental," was inspired by a statement made by Gene Coon, while he and Gerrold were seeking a villain for the installment. Gerrold recounted, "The threat has to come from outside the Federation.' And when he said that, something went twang in my mind, something I'd seen on a first-season rerun – I opened my mouth, wondering what I was going to say, and said, 'Klingons!' [....] Perhaps the fact that I had just seen the episode the week before had something to do with it." Gerrold believed the Klingons fit perfectly into the story. (, pp. 80-82) He subsequently asked Coon if he could reuse them as the alien menace required for the episode. ("The Trouble with Tribbles" audio commentary & Starfleet Access, TOS Season 2 Blu-ray) "He said, 'You know, we've been talking about having a continuing threat, a continuing nemesis for Kirk, and the Klingons are probably the best way to go," recalled Gerrold. ("The Trouble with Tribbles" audio commentary, TOS Season 2 Blu-ray) Despite Coon revealing that the producers had been discussing the option to have the Klingons become a recurring nemesis, he also mentioned that there hadn't been a suitable story form to feature their return, so he gave Gerrold the go-ahead to write them into "The Trouble with Tribbles". ("The Trouble with Tribbles" Starfleet Access, TOS Season 2 Blu-ray) Coon approved of this course of action in agreement with Gerrold's belief that the Klingons were a good fit for the story. Gerrold commented, "This would fit in nicely with his overall plans for the series." (, p. 81) Concluded Gerrold, "So, the tribble episode was where we made the decision to have the Klingons be the continuing nemesis for the Enterprise." ("The Trouble with Tribbles" audio commentary, TOS Season 2 Blu-ray)

Klingon Psychology was one of several topics which David Gerrold thereafter found himself having to hurriedly research before writing the episode's teleplay. Even so, while scripting the installment, Gerrold temporarily had some slight difficulty with making the Klingons as nasty as Gene Coon wanted them to be. Coon thoroughly approved of another element of the episode's Klingons, though, Gerrold later recalling, "Gene Coon thought the names I used for the Klingons were deliciously evil-sounding." (, pp. 121, 135 & 186)

In the script for "The Trouble with Tribbles", David Gerrold described both Koloth and "the last Klingon commander that we saw" as "an evil-looking S.O.B." The last Klingon commander featured on Star Trek before that episode was Kras in "Friday's Child", though Gerrold's comment was most likely aimed at the highly influential character of Kor from "Errand of Mercy". (These Are the Voyages: TOS Season Two)

David Gerrold thought up the idea of Klingons hating tribbles (and vice versa) as a way of determining, in the story, the true identity of Arne Darvin as a Klingon spy. Gerrold later recalled this story point having come to him "almost at the last moment" and said, "It just came to me on the spur of the moment." (These Are the Voyages: TOS Season Two)

The overbearing nature of the Klingons in "Errand of Mercy" influenced Charlie Brill's depiction of Arne Darvin in "The Trouble with Tribbles". Brill was pleased that, because Darvin was a Klingon disguised as a Human, he didn't have to wear the Klingon makeup. 

William Campbell approved of how the Klingons are portrayed in "The Trouble with Tribbles", with the character of Korax being what Campbell perceived as "the nasty one," as opposed to his own character of Koloth. Said Campbell, "I thought that was a good idea; it gave them depth." (The World of Star Trek, 1994 UK ed., p. 121)

Comic book writer Scott Tipton, who co-wrote the mini-series Klingons: Blood Will Tell, characterized the Klingons in "The Trouble with Tribbles" as generally "very different" from those in "Errand of Mercy". He noticed that they are not only less like Mongol warriors by having less of a swarthy appearance but also by being slightly not as fierce, allowing them to be shown aboard Deep Space Station K-7. "These are kind of more like suburban Klingons," he said. "You know, they're a little laid back, you know, it's like they've been working in an office, they just wanna come in, you know, get some R&R, maybe use a snack room [....] It's enough of a keystone back to what we've seen before that it still feels familiar but it works well because you couldn't put the 'Errand of Mercy' Klingons in this episode, 'cause you wouldn't let those guys onto your space station so they can come have a drink at the bar! So, by the nature of the story, you have to kind of make them a little more refined." ("The Trouble with Tribbles" Starfleet Access, TOS Season 2 Blu-ray)

Regarding the fact that the episode "The Trouble with Tribbles" concludes with many tribbles having been beamed aboard a Klingon ship, David Gerrold supposed about the Klingons, "I'll bet that they didn't let any thoughts of inhumanity trouble them....." (, p. 116) When William Campbell was questioned about what the Klingons did with all the tribbles, he responded, "We ate them." (Cinefantastique, Vol. 27, No. 11/12, p. 98) Dave Rossi imagined that the Klingons were "shoveling these things into the engines" at the end of the episode. ("The Trouble with Tribbles" Starfleet Access, TOS Season 2 Blu-ray)

 continued the analogous use of the Klingons. In that outing, they were meant to represent the Communist foes of the United States specifically during the Vietnam War, which was being controversially fought at that time. (Star Trek: The Original Series 365, p. 222) The species was metaphorically used, in this way, since the very first story outline for "A Private Little War" was submitted. Therein, the Klingons were established as having familiarized some of the inhabitants of planet Neural with rifles. Upon criticizing the story outline, Robert Justman wondered, "Why have the Klingons introduced rifles to this civilization instead of their own particular weapons, which we have previously established in another show? I think I know why, but perhaps we ought to spell it out, so that the audience understands that the Klingons still wish to retain absolute control and don't want this civilization to get too advanced, or to be difficult to handle eventually." Gene Roddenberry was interested in increasing the degree to which the Klingons allegorically resembled North Vietnam, politically. He wrote to Coon, "I think it is terribly important that the Klingons are operating in complete secrecy. It is vital to this story, to the whole logic of it that the Klingons attempt to preserve the illusion that all this is 'normal' planet development; that the people with their guns developed gun powder themselves. Thus, if Earth people interfere, the Klingons can argue that it is Earth people who are upsetting the delicate balance of a world here.… In other words, the situation is even closer to the Viet Nam situation. North Viet Nam tries to preserve the illusion, or at least tried to preserve it for some time, that they were not sending men and materials to South Viet Nam. And that way they insisted it was the United States which was the meddler and the aggressor." Coon thereafter stressed to Ingalls the importance of the Klingons being defeated by Starfleet due to secret instructions to counterbalance them, stating, "If we do not play it this way and it is admittedly the hard way, the Klingons will take over and threaten the Federation, even as the situation is in Vietnam, which is, as I remember, if Vietnam falls all Southeast Asia falls." (These Are the Voyages: TOS Season Two)

While the story for "A Private Little War" underwent development, D.C. Fontana suggested substituting the Klingons with the Romulans, as a way of differentiating the episode from "Friday's Child". Gene Coon was determined to keep making the Klingons recurring villains, though. On the other hand, Robert Justman feared, in common with Fontana, that another "nose-to-nose confrontation between Captain Kirk and his Klingon adversary" was one of numerous factors which made the installment too similar to "Friday's Child". (These Are the Voyages: TOS Season Two)

An undeveloped, untitled story which Alan Dean Foster proposed for a two-parter in the third season of TOS involved a Klingon named Kumara. Foster was told to resubmit the idea for the show's fourth season, though the series was ultimately cancelled at the end of its third season. 

At first, no Klingon ships were intended to be shown on The Original Series. "We had no need for a Klingon ship," stated Designer Matt Jefferies, "nor did we have a budget to do one, or the time to design it or build it." Taking advantage of a merchandising opportunity with Aluminum Metal Toys (AMT), however, the Star Trek creative team eventually designed and built the D7 class model of Klingon ship, which ended up appearing in only one episode. That installment, , was far from a major Klingon story and the Klingons played only a peripheral role in it. () However, the Klingons' physical conflict with the Enterprise in the episode's genesis, a story springboard called "Helen of Troyius" and written by Gene Roddenberry, was a major factor in attracting John Meredyth Lucas to write the episode. (These Are the Voyages: TOS Season Three) The Klingon species was well known to the production staff by this time. Stated Fred Phillips, "We had already established the essential character of the Klingons [....] The Klingon character was [...] clearly defined in several scripts [...] [as] cold and, in a sense, vicious." (These Are the Voyages: TOS Season Three, "Embarking on Season Three: Additions & Changes")

In Jerome Bixby's TOS story "For They Shall Inherit", a colony of Klingons residing on a farming world near the Federation border was endangered by the planet's sun being about to go nova, so the Enterprise was sent to rescue them. As discovered by a landing party from the Enterprise, though, the Klingon colonists were now dead, all seeming to have been tortured; they had been subjugated by a malevolent race called the Dorn and all the weak Klingons had been killed by them, sparing only the strongest warriors. The Klingon survivors were forced by their oppressors into fighting against larger, stronger Dorns, in gladiatorial games which the Klingons always lost. A small group of hate-filled Klingons were pitted against the Starfleet landing party, as part of the Dorn's sadistic contests. At one point, Kirk asked the Klingon leader, Tarnok, "Why didn’t you warn us?!" Tarnok replied, "Humans can't find out such things for themselves?" Kirk retorted, "We came to help you!" Tarnok concluded, "And you failed." Discovering that the Dorn fed on hatred and violence explained why only the strongest Klingons were being kept alive, as "food" the Dorn required. The Klingon survivors thus made a concentrated effort, along with the group from the Enterprise, to contain their anger and hatred, instead displaying merriment and conviviality. This behavior weakened the Dorn, who met their doom in the supernova while the remaining Klingons escaped aboard the Enterprise. Paraphrasing Biblical scripture, Dr. McCoy told Tarnok, "Blessed be the meek – for you shall inherit another planet. Hopefully without any Dorns on it." This story outline, the first draft of which was delivered on , gradually evolved into third season's . (These Are the Voyages: TOS Season Three, , )

In a second revised outline Jerome Bixby submitted on  (by which time the episode had been retitled "Day of the Dove"), the colony that was on the edge of Klingon and Federation space and needed to be saved by the Enterprise was changed from being Klingon, replaced instead with an Earth colony. In a third revised outline by Bixby and dated 28 May 1968, the Klingons no longer faced the Dorn, who had been replaced by an entity which could alter the thinking and memories of the Klingons as well as their Federation foes. Also, the Klingons, assumed responsible for destroying the Earth colony, were now brought aboard the Enterprise as prisoners, with the ship providing the battleground between them and the Starfleet officers. (These Are the Voyages: TOS Season Three)

At one point while "Day of the Dove" was in development, Robert Justman wrote to Fred Freiberger, "I venture to state that we would be better off with the Klingon Empire as a running antagonist in this series if we did not establish that there might be some Klingons who can determine that in this particular instance, discretion would be the better part of valor -- but let us never set up a situation whereby those adversaries of ours give any indication of ever being anything but highly aggressive and self-seeking opponents." (These Are the Voyages: TOS Season Three)

In an early story outline for "Day of the Dove" (dated 3 June 1968), Uhura was to have made a remark, while sitting at her communications station early in the installment, which smacked of "hard-core racism against the Klingons," entirely unsure why she made such a comment. At the end of the episode, Captain Kirk was to have mused that the Klingons might become more like the Humans by developing a love of peace, the captain pondering, "Perhaps someday the Klingons will learn the truth of it." Neither of these moments were included in the episode. Similarly, the group of Klingons who, in both the outline and the outing's final version, beam aboard the Enterprise was originally to have included numerous women as well as the female Mara, all of whom (except for Mara) were implied as being a "harem" for the service of the Klingon warriors. 

During "Day of the Dove"'s post-production, a scene featuring the leader of the Klingons, renamed Kang, and Mara was deleted. The scene, which took place on the Enterprises bridge, made it clear the Klingon troop was being dropped from the Enterprise on a neutral planet near the Klingon/Federation border. Cautioning the Klingons against warring, Kirk referred to the idea that, without cooperation, fighting "uselessly, for all eternity" is the result as "a universal rule you Klingons had better learn." (These Are the Voyages: TOS Season Three)

The first draft script for  (dated 7 June 1968) established that the Klingon Empire had been trading with the Romulan Empire. Also, Spock referred to the Klingons, in duplicitous conversation with the Romulan Commander, as "known to have little honor."  In fact, D.C. Fontana included, in the same first draft teleplay, a couple sections of dialogue where the Klingons' alliance with the Romulans was spoken of with concern by Kirk and his crew. Fred Freiberger and Arthur Singer removed these references. Consequently, an account of the Klingons' treaty with the Romulans – explaining why the Romulans were now using formerly Klingon ships – had to be provided for the fans afterwards, in Ruth Berman's column of the official Star Trek newsletter, Inside Star Trek. (These Are the Voyages: TOS Season Three)

The Klingons were not always portrayed allegorically. Years after playing Kang in "Day of the Dove", Michael Ansara declared, "We weren't playing them to resemble any earthly nationality or race. We were from Outer Space." ()

No specific rules were ever stipulated for writing about Klingons. "They had a certain culture and a certain kind of way of thinking that we didn't really line out in the bible or anything like that but we knew from past experience on other scripts how we had developed them," D.C. Fontana reflected. "So, if a writer was going to use them, we just let them read those other scripts or watch the episodes, so they could get a handle on it." 

D.C. Fontana was highly approving of several of the actors who played Klingons, enthusing, "We had some really good ones."  Klingon-playing performers John Colicos and William Campbell, who featured as Kor and Koloth in "Errand of Mercy" and "The Trouble with Tribbles" respectively, were veteran television actors. ()

Although no Klingons ultimately made any more than one appearance in the original series, Gene Roddenberry believed the series could benefit from a regular Klingon character, a counterpart of Kirk's with whom he would frequently clash. As such, both John Colicos and William Campbell were intended to return as their respective characters of Kor and Koloth. Campbell played Koloth in the knowledge that he might subsequently be hired for as many as thirteen episodes per season. Though Colicos was asked to reprise his role as Kor in both "The Trouble with Tribbles" and "Day of the Dove" whereas Campbell was invited for the first of what was meant to be multiple reappearances as Koloth, other commitments kept both actors from returning. (The World of Star Trek, 1994 UK ed., pp. 120 & 121; Cinefantastique, Vol. 27, No. 11/12, p. 61; "The Trouble with Tribbles" Starfleet Access, TOS Season 2 Blu-ray)

The Klingons' appearance changed within the original Star Trek series; although dark makeup and heavy eyebrows were the norm, the Klingons of "The Trouble with Tribbles" were much lighter-skinned and more Human-like in appearance. Regarding this change, William Campbell remarked, "Mike Ansara had a certain gypsy look to him, and John Colicos actually used the name Genghis when describing his character and the kind of make-up. My character in 'The Trouble with Tribbles' was just a guy with a widow's peak and a beard, so basically, we looked like they [the actors playing Humans] looked." () Explained Robert Justman, "The second time [the Klingons appeared], something went wrong. I didn't see them in their makeup before they were photographed, as I usually did. The first time I saw the Klingons revisited, I was horrified. They were much paler and didn't match what we'd done before. I blew a gasket, but in television, unless it's a total disaster, you can't afford to reshoot. The third outing, we went back to them being darker." () Trying to account for these makeup differences, Ruth Berman stated they were "Because there are different races of Klingons, just as there are different races of Earthmen. Also, because, when Fred Phillips looked up information on Klingons for 'The Trouble with Tribbles', the photos he found were poorly lit and gave the appearance of light skin and ordinary eyebrows. Since then, he has followed the 'Errand of Mercy' style of Klingon." (These Are the Voyages: TOS Season Two)

Another changing element was the depiction of Klingon females. A line by Koloth in "The Trouble with Tribbles" was meant to suggest that females ("non-essentials," as Koloth puts it) don't serve on Klingon vessels. (, p. 187) In "Day of the Dove", however, two women (including Mara) are shown as crew members from Kang's battle cruiser. "Day of the Dove" marks the only appearance of any female Klingons in the original series. It was Fred Phillips who created the female variant of the Klingon makeup. (The Star Trek Compendium, p. 119)

Gene Roddenberry always wanted the TOS Klingons to look more alien than they did, but this desire was stumped by TV budgets of the era. () Additionally, Roddenberry was unsettled by the way Klingons were portrayed on the original series, coming to realize that they were at loggerheads with the ethos of Star Trek by being shown as entirely villainous. (; The Making of Star Trek: The Motion Picture, pp. 215-216) In , Susan Sackett relayed about this opinion of Roddenberry's, "He believes that the Klingons emerged as too simply the epitome of evil – the bad guys who always wear black – whereas one of Star Treks philosophical cornerstones was that there are many forms of truth, and other life forms (or other humans, for that matter) should not be branded good or evil solely on the basis of our own customs." (The Making of Star Trek: The Motion Picture, pp. 215-216) During a SeaTrek convention a decade later in , Majel Barrett agreed, "Gene [Roddenberry] never did like the Klingons because they were represented as being 'all bad.' Gene said, 'There is no such thing as a whole race that is all bad.' He really hated that." (Cinefantastique, Vol. 22, No. 3, p. 20)

D.C. Fontana personally found the Klingons less interesting than the Romulans.  Comparing the two groups, she stated, "[The Klingons] were interesting villains with an agenda, not quite as mysterious as the Romulans. The Romulans were a keepout group. The Klingons were operating in our territory which could lead to more direct contact–and conflict–with the Federation." ()

David Gerrold wrote, "All of the Klingon episodes were, in one way or another, restatements of the original: Klingons and Earthmen must not fight." He also approved of the Klingons, if they were to be shown on a regular basis, as not engaging in all-out conflict with the Federation, saying, "Not only does this provide a good background for a wide variety of stories, both humorous and dramatic, but it is a lot more optimistic and (hopefully) believable than a space war. After all, a race that can achieve space travel is going to have done so only through large scale programs of social cooperation, and it is hoped, in the process will have learned that there are better ways than aggression to accomplish one's goals." (The World of Star Trek,  UK ed., p. 32)

The portrayals of Klingons in TOS are largely consistent with one another, though new attitudes were attributed to them in later years. Whereas TOS Klingons were played with what Robert Justman once termed bravura, no one thought of them as honorable warriors yet. "When you got right down to it," said Justman, "they were worthy adversaries and they were killers. They were 100 per cent bad, evil, motivated by the need to be evil. They were thrilled to be evil." () Mike Sussman pointed out, "They really seemed much more interested in glory and treachery than honor in those days. Maybe they found the whole 'honor' thing wasn't working for them." () Quark actor Armin Shimerman noticed that the TOS Klingons are "sort of one dimensional bad guys." (Cinefantastique, Vol. 28, No. 4/5, p. 48) Richard Arnold pointed out they "were not very bright," either. () Ronald D. Moore felt the original series included "very, very little" about Klingon culture. ( audio commentary, TNG Season 3 Blu-ray) He elaborated, "They were villains, it was built around conquest, and there were certain attributes you could identify, but there wasn't that much to go from." ()

After TOS 
While working on Remastered TOS, neither Dave Rossi nor Michael and Denise Okuda were ever tempted to add computer-generated wrinkles to the Klingon foreheads, matching the look of the species in later appearances. "Although, I gotta tell ya, the three of us talked about it for a while," recalled Mike Okuda, "and we thought, 'We should propose digitally retouching the foreheads just so we could see [Visual Effects Supervisor] Niel Wray's head explode,' because once he figured out the amount of time it would take to retouch every single frame with every single scene with every single Klingon, they'd still be working today." ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray)

While  was in early development during , one of three never-produced story outlines which were submitted by Don Christensen and were considered for production by Filmation was entitled "Klingon Attack". (Star Trek Magazine Souvenir Special, p. 55) Klingons subsequently represented one element which David Gerrold felt he undoubtedly had to "shoehorn" into the animated episode . () The installment's creative staff even copied the way the Klingons were used in "The Trouble with Tribbles", involving diplomatic relations between them and Captain Kirk. Gerrold felt a recap in the episode's dialogue was necessary to address the species' hatred of tribbles. ("More Tribbles, More Troubles" audio commentary, TAS DVD special features) However, Klingons turned out to be an aspect of the episode which amounted to it seeming "contrived" to him. () Only one other installment of the short-lived animated Star Trek series featured Klingons: . In "More Tribbles, More Troubles" and "The Time Trap", the same animated footage was evidently used for the Klingon characters of Koloth and Kuri respectively. Making both Klingons look identical was done as a money-saving exercise. ()

In , the Klingons were planned to feature in the ultimately never-produced film Star Trek: Planet of the Titans. The Klingons would have fought with the Federation over a planet once owned by a technological super-race. According to the director, Philip Kaufman, one of the Klingons, hopefully played by Toshiro Mifune, would have battled with Spock while both characters were "tripping out in outer space." (The A-Z of Star Trek, Special SFX Edition, p. 106)

During development of the unrealized TV series Star Trek: Phase II, John Meredyth Lucas wrote a two-part episode entitled "Kitumba" which, if filmed, would have established a radically different Klingon culture to the one developed in subsequent series and films. For a start, it would have been revealed only members of the Empire's warrior caste are called Klingons. The other castes are called the technos, who are the scientists and technicians, and the subjects. A relationship similar to the Emperor and Chancellor in later series would also be established, with the ceremonial Kitumba residing on the Sacred Planet that orbits closer to the sun, while the Warlord presides over political and military decisions on Ultar, the story's name for the Klingon homeworld. (Star Trek: Phase II - The Making of the Lost Series) In essence, the Klingon Empire of this story took major influence from Japan. (The A-Z of Star Trek, Special SFX Edition, p. 105) Lucas explained, "I wanted something that we had never seen before on the series, and that's a penetration deep into enemy space. I then began to think how the Klingons lived [....] The Japanese came to mind, so basically that's what it was. You know, the sacred Emperor, the Warlord and so on." (, issue 112, p. 34)

Film redesign 

Beginning with , improved makeup techniques and bigger budgets led to the Klingon makeup design becoming more elaborate than it had been in TOS. Faced with the prospect of having much more finances to work with for the Klingons in The Motion Picture, Fred Phillips initially asked Gene Roddenberry if he could do some very alien-looking Klingons, a request Roddenberry approved. () "They decided to make aliens true aliens, and so that's how it happened," commented Michael Dorn. "I guess they never thought that they'd have to deal with [fictionally explaining] it at some point." (Cinefantastique, Vol. 32, Nos. 4/5, p. 94) Not only did more finances assist with the creation of a cinematic version of the Klingons for The Motion Picture but so did more time. Both elements enabled Phillips to give "character" to the Klingon faces. (Star Trek: The Original Series Sketchbook, p. 209)

Costume Designer Robert Fletcher was instrumental in giving the Klingons a new "look" for The Motion Picture. Maggie Schpak noted, "We had a lot of time [...] so Bob just designed and designed and designed those Klingons." ("Klingon and Vulcan Costumes", /Blu-ray))

The new makeup design included the original complexion and facial hair of the TOS Klingons but also added a bony head crest. () The head thus became one of the most significant features in the Klingon makeup scheme. "The rest of the makeup was lots of hair and a beard," stated Mark Lenard. "There is a lot of hair on the sides of the Klingon appliances." ( #42, p. 24)

The inspiration for the post-TOS Klingon makeup came from Planet Earth, an unsold  Gene Roddenberry pilot which starred Diana Muldaur and Ted Cassidy. (Cinefantastique, Vol. 37, No. 2, p. 40) That pilot featured a Klingon-inspired, warlike race of mutant Humans called the Kreeg who had ridges down the center of their foreheads. Robert Fletcher was largely responsible for the addition of the Klingon cranial ridges. "I did sketches for the Klingon, including the knobby forehead and head. The makeup department, very generously, said, 'That's great, we'd like to use it.' Gene Roddenberry was not too enthusiastic. He thought they should look more like just people. I said, 'Yes, but these are real aliens, and they're evil aliens.' I think the people, the audience, wants to see something that is not just folks, that goes beyond just folks." ("Klingon and Vulcan Costumes", /Blu-ray)) In production notes Fletcher wrote about the movie's various aliens, he specified about the Klingons, "Spine comes up over head and down forehead (different from series). Hair on side of head as though trying to cover spine." (The Making of Star Trek: The Motion Picture, p. 133)

It was Gene Roddenberry's idea that the newly added head ridges were actually an outgrowth of the Klingon spinal cord, proceeding up the back of the neck and over the head. () Robert Fletcher was of a similar opinion. While considering the Klingons as "a race of reptiles," he also thought their distinctive spines were from a type of crustaceans. (The Making of the Trek Films, UK 3rd ed., p. 52) "In my mind, all the bumps on the forehead and so forth are vestigial remains of a people that evolved like crustaceans, like lobsters, who have their skeleton on the outside of their bodies," Fletcher explained. "And over the millions of years, they've lost that complete outside skeleton, but now retain only vestiges of it." ("Klingon and Vulcan Costumes", /Blu-ray)) Fletcher also believed that the evolutionary roots of the Klingons were symbolized by an ornamental spine piece that runs down the back of some Klingon uniforms, such as those designed for and shown in The Motion Picture. ("Klingon and Vulcan Costumes", /Blu-ray))

Once thought up, the Klingon head ridges required considerable experimentation. "Fred Phillips did a makeup test by putting a bald cap on the actor and sculpting the entire thing out of mortician's wax so he would have a crude version of what it looked like in three dimensions," Rick Stratton explained. However, Director Robert Wise – thinking the test makeup was slightly too extreme – was inspired by noticing the knuckles of one of his hands in moonlight. "He had the idea for a more subtle bone structure than the big gnarly spinal cord thing," continued Stratton, "but we thought to ourselves, 'Oh, knuckleheads!' So we did a makeup test with the subtle 'knuckles,' but it wasn't extreme enough. So, we went back to the more vertebrae-like look." () Stratton also noted of the final design, "It might have looked like a lobster tail." ()

The head piece came down over the brows and back over the head. "It was made in two segments, and they were joined together with cement," reported Mark Lenard. One of these parts was a nose piece that extended down from the upper area of the head piece, over the actor's nose. "So that was pretty warm," said Lenard of the entire head piece. ( #42, p. 24)

The creation of the prosthetics meant the makeup team had to take molds of the actors' faces. ( #42, p. 26) The Klingon appliances were sculpted by Rick Stratton along with Mark Seigel and Mike LaValley. (Star Trek: The Original Series Sketchbook, p. 209) Commented Mark Lenard, "The fellows who did the mask, helpers of Fred Phillips, weren't my idea of professionals. They kind of left you alone. And they took a long time putting it on." ( #42, p. 24)

While helping to sculpt the prosthetics, Rick Stratton suggested adding teeth. "When we began running out of stuff to do," he admitted, "I wanted to get an extra day's pay, so I said, 'How about if we make some messed-up teeth for these guys?' It would save time staining their teeth and make them look like they had been chewing on bones or something, but it was all because I wanted another day's pay!" () The dental appliances remained as part of The Motion Pictures Klingon makeup. (Star Trek: The Original Series Sketchbook, p. 209)

Ve Neill arranged the Klingon makeups for usage, actually applying the makeup for The Motion Pictures main Klingons, of which there were three. () This required the actors to spend several hours each day just being made up for their Klingon roles. Mark Lenard calculated that this duration was between one-and-a-half to three hours, a time span which varied to enable the makeup artists to redo the makeup in time for the beginning of the day's shoot. ( #42, p. 24) "I put all the heads together, dressed the hairpieces, and glued all the hair on the heads [....] Fred [Phillips] hired some old cronies to do the rest of them, and they came in and brushed out all the hairpieces!" Neill remembered. "All they had to do was put on the heads with the hairpieces on them, and take a rat-tail comb and blend the hairpieces onto the heads, but they brushed them all out, and totally messed up all of the makeups. Every one of those actors came to me and said, 'Hey, you've got to fix my makeup!' and I had to say, 'Oh, no, I'm not going to fix anything!' I don't want any of those old guys mad at me!" ()

Once applied, the Klingon makeup in The Motion Picture was so elaborate that it obscured the faces of the actors. In fact, the only way to tell the Klingons apart from one another, according to Mark Lenard, was the build of their bodies. "One was skinny, another fatter, another taller," noted Lenard. ( #138, p. 35)

Gene Roddenberry tried to explain the differences between The Motion Pictures Klingons and the original ones by saying that the original show had simply never had the budget and makeup technology to envision the species as it should have been seen, so the apparently new Klingons were just Klingons as they were always intended to have been. (Cinefantastique, Vol. 37, No. 2, p. 40) He additionally contemplated, "Just as there are different races of humans, there are different races of Klingons, and the Klingons seen in Star Trek: The Motion Picture are not the same race as the ones we saw on the original series." Since Fred Phillips expected that the fans would wonder about how the Klingons could possibly have head ridges newly added to their faces, he and Roddenberry came up with the explanation of there being a variety of Klingon races, even before the release of The Motion Picture. () According to Michael and Denise Okuda, the two men "reportedly joked that the difference was because only 'southern' Klingons were seen in the original series, but those seen in the movies were 'northern' Klingons." () Despite this, the transformation continued to be regarded as a mystery, and would not be addressed onscreen, for decades to come. 

Roddenberry also stipulated that the Klingons would preemptively attack any foreign entity discovered within Klingon space, such as they do to V'Ger in The Motion Picture. (audio commentary, )

Mark Lenard admitted that, before playing the Klingon Captain in The Motion Picture, he had never imagined playing a Klingon and said this was "because they are the arch enemies of the galaxy." ( #42, p. 24) The actor had trouble with the film's Klingon prosthetics, though, complaining, "This Klingon makeup was very uncomfortable and painful." ( #117, p. 48) He clarified, "[It] was so full of hair, and it was so hot–and it itched." ( #138, p. 35) Despite the discomfort, Lenard found that the makeup was sufficiently movable for the required performances, remarking, "Oh yeah, you could be expressive – even as a Klingon." ( #42, p. 26) Richard Arnold once noted that, despite appearing in only a few brief scenes, Lenard was instrumental in developing a key aspect of the Klingon character. Arnold specified that, by making the Klingon Captain "sympathetic," Lenard changed the Klingons "into having more honor." ()

The Klingon style for all subsequent Star Trek productions was influenced by the design of the Klingon bridge in The Motion Picture. (The Art of Star Trek, p. 171)

Gene Roddenberry planned for the second Star Trek film to focus on the Klingons, including an exploration of their culture and the motives regarding their passion for battle. (The Making of Star Trek: The Motion Picture, p. 215) He specifically wanted the second movie to feature a group of Klingons who, having discovered the Guardian of Forever, had traveled through time to 1963 Earth. There, they had prevented the assassination of John F. Kennedy, though their efforts were ultimately thwarted by the crew of the Enterprise, which had followed the Klingons into the past. However, this storyline did not come to be, instead rejected by Paramount. (Inside Trek: My Secret Life with Star Trek Creator Gene Roddenberry, "Log Entry 21" & "Log Entry 22")

Star Trek III 

Although Harve Bennett originally planned for the Romulans to be the primary villains in , the Klingons were instead made the film's adversaries at the recommendation of Leonard Nimoy, as he convinced Bennett that the Klingons were Star Treks main antagonists. () "I've always been more intrigued by the Klingons," Nimoy conceded, "so I suggested the switch, which Harve readily embraced [....] It was Bill Shatner who reminded me that Gene Coon [...] gave us the gift of Klingons." (I Am Spock, hardback ed., p. 223) Nimoy also perceived that the addition of the Klingons was made out of considerations regarding the Genesis Device, which had been established in . "They would have heard about it and would have been threatened by it," Nimoy supposed. "It had overtones of a Soviet-US kind of combat." (Captain's Log, /Blu-ray)) Bennett himself added, "That gave us the perfect foil [....] And, of course, Leonard had a marvelous insight into what they should look like. His knowledge of how we could do it made the Klingons the perfect fit; we had our Nazis." () Bennett also related, "It was only as I was writing it that I realized the Klingons were as dastardly a group of heavies [as the Romulans], and that I had made them so. I'd resurrected them from the series, where they were ill-defined or non-defined." He revealed, too, that his decision to replace the Romulans with the Klingons as the movie's villains was because, after viewing all the episodes of TOS, he perceived a "sense of determination and absolutism" in the Klingon episodes that he felt wasn't so evident with the Romulans. (Star Trek III: The Search for Spock audio commentary, /Blu-ray))

In Star Trek III, Leonard Nimoy wanted to thoroughly explore the Klingon mindset. "My thrust always was, 'Let's learn something,' and I think that's the best of Star Trek, always. 'Let's get under the skin of these characters, under the skin of their story, under the skin of their society. Why are they so paranoid [...] angry and hostile?" (Star Trek III: The Search for Spock audio commentary, /Blu-ray))

One unrealized plot thread from Star Trek III, conceived and briefly considered for inclusion, was that the Klingons had stolen a Bird-of-Prey from the Romulans (accounting for the reused name). "We agreed that the Klingons would steal the best from anybody," Harve Bennett recalled, "though we didn't have time to show it in the story." () Another changed concept was that, on the surface of the Genesis Planet, the Klingons were originally intended to meet with fierce, carnivorous "rock eels", which were physically planned in concept drawings. One of the Klingons was even devoured by an eel. As the character of the Klingons continued to develop, it became clear that they themselves should be the most ferocious lifeforms on the planet, so the idea of the eels was dropped. (The Art of Star Trek, p. 228) The Klingons also appeared in concept art for Star Trek III, storyboarded to appear much as they had been seen in The Motion Picture. ("The Klingons Attack" and other storyboard sequences,  DVD special features)

Leonard Nimoy believed that having the relationship between Klingons Valkris and Kruge established near the start of Star Trek III was "very interesting and helpful in establishing the context in which the story was going to take place." Nimoy was additionally of the opinion that the audience was taught about an aspect of the Klingon mentality via the on-screen interactions between the two Klingons, particularly that Kruge is willing to sacrifice his beloved Valkris, by killing her himself, simply because she has learned all about the secretive Genesis Device. (Star Trek III: The Search for Spock audio commentary, /Blu-ray))

Klingon aesthetics played into the designing of the Bird-of-Prey, such as Leonard Nimoy giving Art Director Nilo Rodis an idea of what a Bird-of-Prey even meant by showing him an image of a Klingon. "I looked at that and I thought, 'OK, I think I understand," Rodis remembered. Particular aspects that he took inspiration from, in designing the Bird-of-Prey, were the Klingons' color scheme and that they apparently like decoration. "If you look at the Klingons, there is something fairly gothic and art deco about them," Rodis pointed out. "If you notice, they never wear simple, undecorated costumes; it's all kind of metallic and leather, with piping and stuff [....] Also, even though the Klingons aren't green, they are definitely not blue. They lean more toward gray/green." ()

Specifically at the request of Leonard Nimoy, Robert Fletcher was made responsible for duties encompassing Star Trek IIIs redesign of Fred Phillips' redesign of the Klingons. Fletcher collaborated with Tom Burman of the Burman Studio, who fabricated Fletcher's designs; they thus created the third-generation version of Klingons, whose bony foreheads were less pronounced than those shown in The Motion Picture. (The Art of Star Trek, p. 226) "We tried to make them somewhat less brutal, less prominent," stated Fletcher, "so that you get a better sense of the Klingons' individual faces." Burman shared Fletcher's conclusion that the Klingon forehead had to be revised. "It was just too cartoonish, and I didn't want a  look in this movie," Burman related. "There had never been a good marriage between the forehead appliance and the actors' faces. We tried to keep them in character rather than have these obtrusive things on their heads." Burman believed that doing each of the Klingons right took two hours. (The Making of the Trek Films, UK 3rd ed., p. 52) According to Maltz actor John Larroquette, though, application of the makeup required five hours. ( #138, p. 25) The makeup process began with the application of a bald cap and forehead appliance. Still included as part of the makeup was faux facial hair. (Cinefantastique, Vol. 17, No. 3/4, p. 83) Owing to the fact that the makeup artists used a different base on the prosthetic pieces than on the actors' skin, there was a difference between the color of the prosthetics and the skin tones. ( #138, p. 30)

Director of Photography Charles Correll was tasked with using lighting to ensure the Klingon makeup in Star Trek III looked believable throughout the movie, so that any naturally occurring anomalies in the makeup were not highlighted. Given that the bridge set for the film's Klingon Bird-of-Prey was top-lit and deliberately kept dark, Correll said about the Klingons being shown on their own ship, "We were lucky [...] and I think we accomplished what we had to do." The dim lighting not only helped make the Klingon prosthetics less pronounced but also added to how dramatic the Klingons appeared, which the framing of the shots also aided. "Shooting these guys on the Klingon bridge was all about getting in tight, getting mysterious, getting intense," commented Leonard Nimoy. "Very tight, very up-close, intense stuff, to emphasize the power of them, the presence of them, the danger of them, and their conspiratorial attitude, their whispering and the tension that grew out of that." (Star Trek III: The Search for Spock audio commentary, /Blu-ray))

The Star Trek III portrayal of Klingons took inspiration from Japanese history. "Harve [Bennett] had the notion that the Klingons were like Samurai warriors," explained linguist Marc Okrand. () Robert Fletcher agreed with Bennett, later saying of the Klingons, "I always liked to think of them as authoritarian, almost feudal, like Japan had been." (The Making of the Trek Films, UK 3rd ed., p. 52) As such, both the Klingon costumes and Klingonese language in Star Trek III were influenced by the feudal Japanese culture. (The Art of Star Trek, p. 226; ; The Making of the Trek Films, UK 3rd ed., p. 52)

One actor who auditioned for the part of a Klingon in Star Trek III was Robert Beltran. When he walked into an audition with Leonard Nimoy, he forthrightly asked, "So, what's a Klingon?" Though his naivete obviously resulted in him losing the role he was trying out for, Beltran went on to regularly appear as Chakotay on , years afterwards. (The Finest Crew in the Fleet, p. 84)

At one point, Leonard Nimoy remarked that, on Star Trek III, he was "happier than ever to be working with Klingons!" and that this was due to Kruge actor Christopher Lloyd's portrayal in the film. (I Am Spock, hardcover ed., p. 226) For his part, Lloyd once expressed that he thought the Klingon makeup was helpful to performances, commenting, "That kind of makeup, when it’s put on well, it enhances what you’re doing and gives you more confidence that you’re going to be able to portray the character and make it believable."  One drawback of the makeup was that it was difficult to endure. "It was very heavy from the wig all the way down," attested John Larroquette. "It was claustrophobic." ( #138, p. 25)

Multiple Klingon props and hand weapons in Star Trek III were designed by Industrial Light & Magic. (The Making of the Trek Films, UK 3rd ed., p. 53)

Gene Roddenberry didn't find the Klingons in Star Trek III bothersome. This was because they were portrayed with much of the same attitudes as they had always had. (Star Trek Movie Memories, hardback ed., p. 289)

Star Trek IV 
Even by the mid-1980s, Klingon makeup was still extremely thick. Klingon-portraying performers such as John Larroquette, in his role as Maltz, and John Schuck, who portrayed the Klingon Ambassador in  and , were thereby made to look barely recognizable in their Klingon personas. ( #138, pp. 25 & 28) On the other hand, contrasting films of this period with The Motion Picture, Mark Lenard proclaimed, "They've modified the Klingon makeup a bit so now you show a little more of the face and can distinguish who's who." ( #138, p. 35)

Leonard Nimoy selected a single forehead design to be used for all the Klingons in Star Trek IV. (The Art of Star Trek, p. 254) Richard Snell commented, "We did what I called cookie cutter work [....] Basically it was done that way because that's the way it'd been done before." (Cinefantastique, Vol. 22, No. 5, p. 33) Said John Schuck, "It involved taking a full head cast. They bury you under mounds of dental compound, making a positive mold out of that, upon which they built the appliances." The duration required for applying Star Trek IVs Klingon makeup (at least in Schuck's case) was four-and-a-half hours. ( #138, pp. 29 & 30) The actor complained, "It was heavy makeup. Getting it on was hard and, I always say, getting it off was harder." 

John Schuck thought the Klingons had begun to undergo a gradual transformation of ultimately becoming a tad friendlier by the time of Star Trek IVs creation. After discussing this subject with Gene Roddenberry, Schuck recalled, "It seemed to me that in the minds of the creators, the Klingons had matured [....] I asked him about it. He said it was time for the Klingons to take on a dimension which showed that the culture had changed. Alliances change. There can be progress." () The actor also remembered about Roddenberry, "He felt that maybe the time had come for the Klingons – not that they shouldn't be adversaries and a dark, moody group – to be a little more accessible, make them a little more interesting in that way." ( #138, p. 30)

Much of the focus on the Klingons in the Star Trek films preceding the advent of  was not on their culture. Ronald D. Moore perceived, "The movies were sort of more about art direction, sort of how they behaved, and sort of changing their makeup than about anything cultural." ( audio commentary, TNG Season 3 Blu-ray) Regarding the make-up, Michael Westmore observed, "Until now, Klingons were brown. Some had a bony ridge running down the middle of their foreheads, long black wigs and facial hair." (Star Trek: The Next Generation Makeup FX Journal, p. 28)

Becoming heroes 
Immediately prior to the genesis of , the Klingons were planned to be depicted in an ultimately undeveloped idea for a new Star Trek series, which was thought up by the father-and-son producing team of Sam and Greg Strangis. In that discarded series concept, the Klingons were no longer antagonistic and were, instead, allies of Starfleet. (The Fifty-Year Mission: The Next 25 Years, p. 44)

On Star Trek: The Next Generation, Gene Roddenberry was originally averse to Klingons appearing at all. (; ) This was because he wanted to avoid them returning until the new series had been accepted on its own merits. As such, the Klingons were one of several original-series aliens (also including Vulcans and Romulans) which were initially vetoed by Roddenberry. () Another issue that resulted in him planning the omission of the Klingons was that, by the time he opened TNG pre-1987 for story concepts from writers, the Klingon backstory had become so extensive it was now a problem. Said Richard Arnold, "Gene kept getting stories from professional writers about wars with the Klingons and he kept saying, Star Trek is not about Klingons!" ()

Robert Justman began an  memo to Gene Roddenberry, concerning the show's bible, with the sentence, "Despite your aversion to using Klingons in the new series, I think I've thought of something which might just change your mind." Justman went on to propose a resident Klingon serving aboard the Enterprise, suggesting that the military skills and prowess of the Klingon species might cause such a person to be well-suited for a role in the ship's crew. (Star Trek: The Next Generation - The Continuing Mission, p. 15) Roddenberry's response was adamant about excluding the species, saying, "Bob, we've passed all that. We don't need Klingons." However, Justman insistently challenged this opinion, pointing out that the acceptance of a Klingon in Starfleet could imply that Human attitudes had grown, which fit well with Roddenberry's optimistic view of the future. () On , the subject of Klingons was brought up by D.C. Fontana. She proposed that the TNG production staff either leave them as a violent adversary, ignore them, eliminate them entirely, or have them be at peace with the Federation, Fontana suggesting that the fourth option seemed to open the most story opportunities. She pointed out, "Story situations can grow from interaction with ambassadors, trading ships, other 'alliance' vessels with Klingon personnel..." (SciFiNow – Star Trek: The Complete Manual, p. 53) Roddenberry was finally tiring of people asking about Klingons, which led him to authorize the character concept that then became Worf. (Cinefantastique, Vol. 32, Nos. 4/5, p. 92) At last, he agreed that a Klingon alliance with the Federation might be indicated via the inclusion of the new character, limiting the focus on the warlike nature of the species. ()

Whoopi Goldberg once cited the fact that "the Klingons have cooled out" as an indication that "things are going well for the world." ("Mission Overview", TNG Season 2 DVD/Blu-ray special features) On the other hand, she also cited the Klingons as a group of people which the Federation couldn't cooperate with, Goldberg specifying, "I don't care what they do; Klingons are just tough, you know." ("Beyond the Five Year Mission, The Evolution of , Part Three: The Noosphere", TNG Season 6 Blu-ray special features) The adoption of Plan B indeed involved retaining not only the Klingon species itself but also their fierce image of "guys you've got to watch out for," meanwhile having them join the Federation. () Nonetheless, at least in the opinion of Raphael Hernandez – the producer and writer of the CD-ROM game Klingon Academy – the TNG Klingons turned out to be much less "dramatic" than previous Klingons. () Disagreeing, Worf actor Michael Dorn argued that, with the advent of TNG, "the Klingons started talking more like Shakespeare, and they started getting very big." (The A-Z of Star Trek, Special SFX Edition, p. 85) Susan Sackett implied that having the Klingons now be Federation members, a decision made by Gene Roddenberry, was inspired by his efforts to ease hostilities between himself and Paramount, following the rejection of his Klingon-centric script for the second Star Trek film. (Inside Trek: My Secret Life with Star Trek Creator Gene Roddenberry, "Log Entry 35") Though the Klingons ultimately weren't made Federation members, Garfield Reeves-Stevens later reckoned, "You could project into the future that at some point the Klingons might join the Federation." (Star Trek: The Official Starships Collection, issue 55, p. 15) Commented Ronald D. Moore, "The Klingon alliance was cool and interesting because they had been villains on the original series [...] [but] they sort of got defanged." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 101)

In the first writer's/director's guide for TNG, Gene Roddenberry stipulated that "no stories about warfare with Klingons" should be submitted. However, he and the rest of the staff soon realized that TNG had quickly established a style of its own, so they allowed Worf's Klingon background to be explored. (The Art of Star Trek, p. 92) As a result, the Klingons made the occasional guest appearance in the first two seasons of TNG. ()

Gene Roddenberry thought of the Klingons as actual people, often asking himself such questions as "Would the Klingons be happy with that kind of government or philosophy?" He reflected, "You spend years dreaming them up, and they begin to build up into a rather real thing. I don't for a moment think they are real subjects, but they have a reality for me. I take the fact of their fictional existence very seriously. If I am going to write something about them, and they are going to be seen by Arthur C. Clarke or Ray Bradbury, people I love and respect, I have to pretend that they are real, and that this is serious." (Cinefantastique, Vol. 22, No. 3, p. 20)

African-American actors were often cast as Klingons in TNG and subsequent Star Trek productions. This practice wasn't racially motivated but was instead carried out because it lessened makeup time, as the performers already had a brown complexion without having to have their skin painted that color. (Stardate Revisited: The Origin of Star Trek: TNG, Part 2: Launch, TNG Season 1 Blu-ray) Tony Todd, who portrayed the recurring Klingon character Kurn, stated, "I don't look at the Klingons necessarily as African-Americans, but it's about tapping into something–they're certainly an alienated people, so maybe that's why African-American actors can identify with those characters. But that doesn't mean it's exclusive to them." ()

In relation to the casting of Michael Dorn as Worf, Dorn's manager and many people Dorn knew were at first puzzled as to what a Klingon was. Having been a Star Trek fan since the start of TOS, Dorn knew much about Klingons by now and was consequently able to explain the nature of the species to his curious acquaintances. ( issue #138, p. 64) As Dorn and Robert Beltran were friends, Beltran informed Dorn about his unsuccessful auditioning experience for a Klingon role in Star Trek III, a story which influenced Dorn to devise a strategy for his own audition, which he attended with a Klingon mindset. (The Finest Crew in the Fleet, p. 84)

While Michael Dorn was preparing to play Worf, Gene Roddenberry wanted previous Klingons to have minimal influence on the forthcoming portrayal, advising Dorn, "Forget everything you've ever read or heard about Klingons." () Dorn was well aware that the species was intended to be shown in a different light than in TOS. "Roddenberry is saying that even Klingons have redeeming qualities," observed the actor. "That everybody has some good. I agree with him." (The Finest Crew in the Fleet, p. 85) However, Dorn also acknowledged, "Making them allies in the first place flew in the face of what the Klingon race is all about." (Star Trek - Where No One Has Gone Before, paperback ed., p. 201)

The Klingon makeup schemes for TNG were influenced by previous Klingon facial appearances. "I already had the basic design from the motion pictures," Michael Westmore observed. (Star Trek: Aliens & Artifacts, p. 59) However, he wanted to depart from what had gone before, later claiming that the "subtlety of the original ridges did not translate onto television." (Star Trek 30 Years, p. 57) Westmore made his decision of wanting to deviate from the features of past Klingons upon first thinking about the species for The Next Generation and talking about them with the series' other creative personnel. Believing the addition of prosthetic heads was insufficient, Westmore wanted to differ the TNG Klingons not only from those shown in the previous films but also from the Klingons of the original television series. (; Star Trek: The Next Generation Makeup FX Journal, p. 28) "I felt that for such a fierce warrior race, copying old designs just wasn't enough for The Next Generation," Westmore explained. "I wanted to lend a little more ferocity to their overall appearance, so I asked Rick Berman and Gene Roddenberry to let me try something different from what 'had gone before." (Star Trek: The Next Generation Makeup FX Journal, p. 28) Berman offered, "Gene Roddenberry [also] wanted to redesign the look of the Klingons. That's the real reason for the change in appearance." () Altering the Klingon makeup scheme for TNG was considered a positive development because it helped to differentiate Klingons from other species. (Cinefantastique, Vol. 22, No. 3, p. 20) Westmore continued, "It's one area where I had a lot of license with it, because I was given photographs of former Klingons and there were no two alike. They were all different. So, I was given the opportunity to go ahead and create a new Klingon look that hadn't been done yet." ("The Making of a Legend", TNG Season 1 DVD & Blu-ray special feature) The Klingon makeup for The Next Generation was thereafter specifically based on the Klingon look Fred Phillips had developed for The Motion Picture. (The Art of Star Trek, p. 92)

Michael Westmore actually changed the Klingon facial design in numerous ways, though. He stated, "I added a Shakespearean style of facial hair and a forehead bone structure based on dinosaur vertebrae and I was able to modify motion picture Klingons for television." (Star Trek: Aliens & Artifacts, p. 59) He also explained, "I suggested bringing their makeup down into their face by using noses and teeth, rather than having just a forehead." ()

Michael Westmore believed adding a ridged "latex nose," an idea he first thought up while designing Michael Dorn's makeup for the character of Worf, ended up as "one of my biggest changes" to the Klingons. The nose appliance connected into the forehead makeup piece and covered the bridge of the nose, thereby bringing the ridged look previously introduced by the forehead into the center of the actor's face. "The idea turned out to be quite successful," Westmore stated, "and became one of our signatures on the series." Each of the actors portraying a Klingon on TNG had a unique latex nose crafted for him or her. (Star Trek: The Next Generation Makeup FX Journal, p. 28)

After incorporating a nose piece into the Klingon facial design, Michael Westmore hit upon the notion of also including newly crafted Klingon teeth, which he made look discolored, broken and uneven. The teeth were acrylic caps which fit over the performer's own teeth. A unique set of teeth was cast for each speaking actor who was to play a Klingon on TNG. This enabled the false teeth to fit perfectly and have, similar to real teeth, an individual appearance. Westmore routinely issued the teeth to the performers one or two days before the actors began working, so they had time to practice with them. (Star Trek: The Next Generation Makeup FX Journal, pp. 28-29)

Michael Westmore based TNG's elaborate Klingon foreheads on images of dinosaur vertebrae sections, for instance by isolating and studying a small part of a single vertebrae. "There are several books that I used as reference material," he noted. One such book was about the anatomy of dinosaurs. (Star Trek: The Next Generation Makeup FX Journal, p. 30)

An early policy was devised by Michael Westmore whereby each Klingon forehead was cast with a different ridge pattern. Westmore soon came to regret this policy, however. () "As I started sculpting the first forehead pieces for our Klingon guest stars," Westmore revealed, "I was under the mistaken impression that each design had to be different, as opposed to using the same mold more than once. It was the beginning of what I would eventually call 'Klingon Hell'; the self-imposed task of sculpting a new and different head for virtually every Klingon actor [on TNG]." (Star Trek: The Next Generation Makeup FX Journal, p. 29) The makeup department of TNG nevertheless amassed a gigantic backlog of different Klingon foreheads over the years. This was in addition to a supply of different Klingon noses available to the makeup staff. (Star Trek: The Next Generation Makeup FX Journal, p. 28)

At about the start of the series, the duration needed to apply the makeup for a single Klingon was two hours per day. ( issue #138, p. 37) Especially due to the series featuring Worf as a regular character, the Klingon makeup scheme for TNG continued to become more refined throughout the series. (The Art of Star Trek, p. 92) Stated Michael Dorn, "I feel I've been a model for all Klingons." () He elaborated, "I would like to think that I was the next generation of Klingons and because of my character, we really started opening up and seeing what these guys are really like, and it's a very interesting, very interesting show." (Cinefantastique, Vol. 32, Nos. 4/5, p. 92) Indeed, Dorn hoped his influence on the species had been a positive one, saying, "I would like to think I've had a hand in [...] making the Klingons interesting." () Gowron actor Robert O'Reilly enjoyed jokingly telling fans that, because Dorn wore size fourteen shoes and established the mold for Klingons of the TNG era, every other performer of Klingons had to learn to walk in size fourteen footwear. (Cinefantastique, Vol. 27, No. 4/5, p. 107)

A characteristic design ethos was applied to the Klingons on TNG. "Klingon design is very harsh angles," Senior Illustrator Rick Sternbach pointed out, "and the colors are lots of olive drabs, rusty reds, very hard." ()

While having lunch with Gene Roddenberry one day very early in TNG's first season, Susan Sackett pitched a Klingon episode to him. She later recollected, "I told him I wanted to write a story about a group of renegade Klingons who had not seen the wisdom of the new order in which Klingons [...] were now loyal adherents of the Federation." As Sackett proceeded to outline her rough ideas for the plot, Roddenberry kept nodding his head. "When I finished," Sackett remembered, "he said simply, 'It won't work. Not on this show. All Klingons are now loyal.' End of discussion. Not even Gene could foresee the direction the Klingon story arc would take." (Inside Trek: My Secret Life with Star Trek Creator Gene Roddenberry, "Log Entry 37")

Early Klingon forehead prosthetics caused some skin problems. Michael Dorn said, "The glue was the number one thing I had a major problem with." This was remedied, after Dorn complained about it to the producers, in the second season of TNG. () "They changed a lot of the makeup process," he continued, "because my skin wasn't doing very well [....] To their credit they stopped and said, 'OK, wait a minute, let's try to change this." (Cinefantastique, Vol. 32, Nos. 4/5, p. 94) Korris actor Vaughn Armstrong's Klingon forehead prosthetic in the episode  likewise caused him to develop a rash by the time it was first removed, as he had an allergic reaction to the makeup. "They were very concerned," Armstrong related, "because they knew they were going to use it a lot, but they fixed it and it never happened again." ()

It was "Heart of Glory" which introduced The Next Generation Klingons (except for Worf's previous appearances and an illusory Klingon temptress in ). Ronald D. Moore once referred to "Heart of Glory" as a notable episode for developing the Klingons. ( audio commentary, TNG Season 3 Blu-ray) Owing to the Klingon death ritual established therein, Moore regarded the episode as an uncommon insight into the ritualistic aspect of Klingon culture which "left a mark that the Klingons were very ritualistic." () Michael Dorn commented, "For my money, that was the first real Klingon episode of that first season [....] I think that episode worked because it showed Klingons could be eloquent beings. We gave audiences something where they could ask, 'Wait a minute! Who are these people?" (Star Trek Generations - Official Movie Souvenir Magazine) He was also of the opinion that the outing not only inspired questions regarding the Klingons but also answered some. Dorn remarked, "I consider 'Heart of Glory' to be an information episode because it gave you everything you wanted to know about what happened with the Klingons. Why did they become allies? [....] That type of thing." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 165) Dorn thought it "nice to see that they weren't just savages." ( issue #138, p. 38) Another facet of the episode's Klingons that Dorn was pleased with was the selection of actors playing them. "[They] were probably some of the best actors we've had on the show," he enthused. "They were steady, they were strong, they were right there, and it really made it a joy to work with them. You had to rise to the occasion." ( issue #138, p. 38) The outing set a precedent for Klingon mythology that was later to be followed in many other installments. "And I think this is something that they probably didn't realize," Dorn said of the TNG producers and writing staff, "when they started down this road of Klingon stuff, that they were gonna have this mythology." ("Making It So: Continuing Star Trek: The Next Generation, Part 1: Strange New Worlds", TNG Season 2 Blu-ray)

Maurice Hurley, who co-wrote the story and scripted the teleplay for "Heart of Glory", observed that the Klingons helped bring a sense of balance to the series. "With the Klingons you're dealing with emotion and passion. You've got somebody who can say something. You need that balance in the show sometimes," he opined. "The show gets so intellectually smug and self-serving, and you need something like that to break it off; someone willing to storm the barricades." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 182) Additionally, Hurley expressed that "Heart of Glory" presented the Klingons in such a way as to be highly relatable, saying, "The hunter remains within us all. That need to stalk and kill, drink warm blood and howl at the moon is part of who we are." () This approach helped the Klingon-playing actors to find their characters' mindsets. "You always start from the Human element of these people," stated Vaughn Armstrong. "You find out what it is about them that you can relate to, and then you add other little characteristics as you go along and see the makeup, talk to the director, and all of that." ()

Director Rob Bowman was extremely familiar with the Klingons before directing "Heart of Glory", later saying, "I knew the Klingons very, very well from the movies and the original series." () Vaughn Armstrong noted about Bowman, "He also said, 'We want the Klingons to be the bikers of the universe!" () In "Heart of Glory", Bowman introduced the idea that it took three phaser hits to down a Klingon, with killing blows. "I wanted to make these guys as tough and as bad as I could," he said. ("Rob Bowman – Director of a Dozen", )

The Klingon alliance with the Federation was at first meant to feature in the story which became . In the episode's original form, fears that the peace with the Klingons had made the Federation complacent motivated a Starfleet conspiracy based solely on paranoia. The notion of the concern over the alliance was omitted because Gene Roddenberry rejected this early version of the installment. (Captains' Logs: The Unauthorized Complete Trek Voyages, pp. 168-169)

TNG Season 2 
In the interval between the first and second seasons of TNG, Michael Dorn voiced some hopes on how the Klingons might proceed to be developed. "In the future, I would like to see a half-human, half-Klingon," he said. "And I would like to see the Klingons interacting more with the Federation. I don't think Klingons should be that much integrated into the Federation. I love their unanimity, their separateness, because they are such a straight-laced people. Once you start integrating the Klingons too much, they lose their edge." ( #138, p. 38)

Although TNG Klingons had collectively featured in "Heart of Glory",  actor Brian Thompson considered  "the first episode of The Next Generation to venture into the Klingon realm and to give audiences more of an in-depth look at this unique warrior race." (TV Zone, Special #29, p. 56)

Rob Bowman thought the Klingon action in "A Matter Of Honor" made it a fun episode to direct; after doing so, he remarked, "I guess there's a spirit inherent in the Klingons that seems to push it forth in a certain direction with the characters and the camera." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 176)

In "A Matter Of Honor", the Klingons were intended to be used to shed some light on a common social problem prevalent at the time of the episode's making. This was, namely, what it was like to be the only person of either white or black skin coloration while surrounded by people of the other color. The Klingons were selected to illustrate this theme as a spin on the usual arrangement of a predominantly Human crew serving aboard the Enterprise-D alongside Worf. (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 176)

Michael Dorn once cited the Klingon crew in "A Matter of Honor" as rare evidence that Klingons can appreciate humor. "Those Klingons had a wonderful sense of humor," the actor opined. "A very sardonic sort of wit." (Cinefantastique, Vol. 21, No. 2, p. 59)

Producer Burton Armus not only co-wrote the story and wrote the teleplay for the Klingon-centric episode "A Matter Of Honor" but was also interested in an ultimately undeveloped Klingon story that was written and pitched for the series by freelance writer Marc Scott Zicree. This never-produced episode would have established why the Klingons looked differently in the new series and films to how they had appeared in TOS. Though Armus wanted to buy the story concept, he had left the series before he could. ()

Star Trek V 

As co-writer of the story for  and the director of that film, William Shatner observed that the Klingons provided an important structural function to the film's writers. "The Klingons were always regarded as an added threat," he stated. "We kept them alive throughout the story–almost mathematically mapped it out–so that the element of tension would be there. Otherwise, it would become, 'Are they going to see God, or aren't they–yes or no, yes or no,' like Ping-Pong balls. This way the elements of the unknown were kept alive, adding more tension and interest to the story. And, of course, they became an interesting way to resolve the final problem of how to get Kirk back on the ship." Harve Bennett cited the Klingons' rescue of Kirk from  as contributing to the surprises throughout the movie, saying the reveal of the Klingons as Kirk's rescuers was meant as a "big surprise." (Captain's Log: William Shatner's Personal Account of the Making of Star Trek V: The Final Frontier, pp. 51 & 50)

William Shatner was pleased with the casting of Todd Bryant and Spice Williams in the Klingon roles of Klaa and Vixis respectively, commenting, "They were physically right for the Klingons and were obviously talented enough to do the roles justice." These two actors spent a great deal of time preparing for their roles. (Captain's Log: William Shatner's Personal Account of the Making of Star Trek V: The Final Frontier, pp. 78 & 147-148) For instance, because Star Trek V was to be the first time when Klingons with bare arms were shown, Williams and Bryant began to adhere to a strict fitness workout routine and a diet to improve the physical appearance of their bodies. ("That Klingon Couple",  DVD & Blu-ray)

Some of the Klingon-playing actors in Star Trek V revised previous Klingon characterizations. Art Director Nilo Rodis provided Korrd actor Charles Cooper with advice on Klingon culture, recommending Star Trek III and IV to Cooper with the statement, "That's where the Klingons are really presented." ( #149, pp. 60 & 61) Despite Todd Bryant having already viewed all of the earlier Star Trek movies as well as TOS, he rented VHS tapes of the original Star Trek episodes which featured Klingons and repeatedly re-watched Christopher Lloyd's performance as Kruge in Star Trek III. "I looked for their attitude and how they acted toward humans; I tried to find the differences between the two [....] I learned that Klingons were aggressive and warlike, and I added some thoughts of my own, as to what I believed they would be like." Aware that Klingons had originally been patterned after Genghis Khan, Bryant also studied up on famous historical warriors and rented old pirate films that starred Errol Flynn. "It's a conquering personality that all Klingons have inbred in them," he mused. "They all want to conquer the universe." ( #149, p. 63)

Further helping them prepare for their Star Trek V scenes, Todd Bryant and Spice Williams rehearsed extensively together over several eight-hour days, with the intention of absolutely perfecting their performances. ( #149, p. 63) During this period, Williams decided that the Klingons they were playing should be far different from earlier-established members of the species. "We feel we're playing the Klingons as being much more real," she commented. "You can only go so far in creating a race that's only known for its evil. Seeing Klingons as having wants and desires is much more interesting. Vixis and Klaa are the new generation of Klingons. We're like spoiled rebellious yuppie Klingons. We're not just barking commands at each other. We're sharing and exchanging dialogue and we're showing that there's more than just a working relationship between the two. How Klingons are portrayed in Star Trek V appears to be the historical link when Klingons stopped being the committed enemy of the Federation and began working with them. The fact that a Klingon plays a prominent role in Star Trek: The Next Generation probably results from what takes place in Star Trek V." ( #149, p. 67) The notion that, typically, the Klingon hierarchy would never permit a female Klingon first officer to become a captain was central to the portrayal of the relationship between Klaa and Vixis. Williams explained about herself and Bryant, "We both love Star Trek, we both saw an opportunity to contribute something far greater, a relationship, back story, and we literally sat down [...] and we would go through, 'Who are we? What are we doing here? Why are we here?' I mean, we even discussed, I think, 'What do Klingons brush their teeth with?' And I think Todd said, 'They don't brush their teeth.' That was brilliant!" ("That Klingon Couple",  DVD & Blu-ray)

Part of conceiving the back story regarding Klaa and Vixis involved Spice Williams and Todd Bryant imagining the nature of the connection between the characters. Said Williams, "We wanted this sensual, sexual relationship that was never done before." Bryant offered, "[It] was something I don't think people got because they cut it out of the film. It's a lot of guesswork there but, yeah, there was a lot of that going on, undercurrent that we had a serious relationship that no-one was supposed to know about." ("That Klingon Couple",  DVD & Blu-ray)

According to Captain's Log: William Shatner's Personal Account of the Making of Star Trek V: The Final Frontier (p. 148), Todd Bryant and Spice Williams had to endure a three-hour makeup session each morning to look sufficiently Klingon. According to  #149 (p. 64), however, Bryant's makeup required a daily duration of four hours to be put on. He himself specified, "We'd both get there real early, 3.45 a.m. for an 8 o'clock or 9 o'clock a.m. call. So, we'd be sitting in the makeup chair for a good four hours." ("That Klingon Couple",  DVD & Blu-ray) Charles Cooper's makeup as Korrd took four-and-a-half hours to apply and an hour to remove. ( #149, p. 62)

For each of the performers cast to portray a Klingon in Star Trek V, the application process began with a bald cap being positioned over the performer's hair, after which one of the Klingon forehead appliances was added. (Captain's Log: William Shatner's Personal Account of the Making of Star Trek V: The Final Frontier, p. 148) William Shatner permitted Richard Snell to produce each of the film's Klingon foreheads as a distinctive design. "I always felt that their foreheads should be like a thumbprint," admitted Snell, "and on V, Shatner said, 'Go ahead, make 'em different.' I thank him for that. That opened the door and now the sky's the limit." (Cinefantastique, Vol. 22, No. 5, p. 33) The forehead prosthetic was attached to the actor's skin using a strong adhesive glue. Both the newly added appliance and the skin were then painted with makeup, which was a mixture of acrylic and adhesive. Each performer then donned a hairpiece, helping complete the illusion. Unlike Todd Bryant and Spice Williams, Charles Cooper underwent an additional step in the procedure, as his makeup was completed with a layer of KY jelly that was used to give his skin a slick, oily appearance. (Captain's Log: William Shatner's Personal Account of the Making of Star Trek V: The Final Frontier, pp. 148 & 149) The only Klingon which Makeup Effects Artist Kenny Myers created for Star Trek V was a Klingon god, of which he said, "I knew I wanted something that would imply a little more history to their race." In an attempt to imbue a sense of Klingon evolution in the design, Myers redesigned the forehead slightly, so it was a little higher than usual. (The Making of the Trek Films, UK 3rd ed., p. 90)

Unusually, Todd Bryant enjoyed being in the heavy, dark makeup required for his appearance as a Klingon, as well as the big wig associated with Klaa. He subsequently noted, "There wasn't really a sweat problem. It didn't really get that hot." ( #149, p. 64)

Given the extreme degree of preparation involved, William Shatner was very excited to film the Klingons. He was not disappointed, thrilled with the performances of Spice Williams and Todd Bryant. (Captain's Log: William Shatner's Personal Account of the Making of Star Trek V: The Final Frontier, pp. 147 & 148) Indeed, the efforts they had gone to in order to prepare for their Klingon roles turned out to be successful. "It worked," stated Bryant, "because, by the time we got there, we were so well-versed and we knew exactly how it was going to be blocked; everything went very quickly, and we did one or two takes most of the time." ( #149, pp. 63-64) Commented Williams, "Todd and I were so well-rehearsed that they were able to shoot all our scenes in three days. In fact, Shatner would come up to us after almost every scene and say something like, 'You're the most well-rehearsed actors I've ever seen." ( #149, p. 67) The pair of actors continued their diet even during production. Williams noted, "We were eating cans of tuna before shooting a scene." ( #149, p. 64)

As with the Klingons in Star Trek III, Gene Roddenberry wasn't bothered by the Klingons in Star Trek V. Again, this was due to them being portrayed with much the same attitudes as had been usual for them. (Star Trek Movie Memories, hardback ed., p. 289)

TNG Season 3 

At one stage, Ron Moore cited  as a significant installment for developing the Klingons. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) Brannon Braga, who later served on the writing staff of TNG, and Moore agreed that Michael Dorn and K'Ehleyr actress Suzie Plakson were "very good together," first acting alongside each other in "The Emissary". ("Reunion" audio commentary, TNG Season 4 Blu-ray) Dorn himself, however, wished the episode had gone deeper into the relationship between Worf and K'Ehleyr, feeling the installment merely "scratched the surface" and that the idea of the romance was "sort of a teaser." Countering this opinion, Story Editor Melinda M. Snodgrass remarked, "I think there was a lot of heat." In crafting the episode's plot, the TNG writing staff toyed with the concept of the Klingons having allied themselves with the Federation without actually having become members of the organization. "That gave us something to play with," noted Snodgrass. (Cinefantastique, Vol. 21, No. 2, p. 45)

At the time Ron Moore wrote his first produced episode for TNG, season three's , he had become interested in the Klingons and had read about the species in the novel The Final Reflection, a book which had shaped much of his thinking about Klingons. ("The Bonding" and "Sins of the Father" audio commentaries, TNG Season 3 Blu-ray) Indeed, he had also begun considering several aspects of Klingon culture, concepts which he explored in "The Bonding". These ideas included Klingon honor, Houses and bonding people to them. However, Moore was unaware he was about to become synonymous with Klingon episodes. "I certainly didn't anticipate [...] that I would keep embellishing," Moore admitted, with a laugh, "on this culture, over and over again, throughout my Star Trek tenure." ("The Bonding" audio commentary, TNG Season 3 Blu-ray)

Klingons were present in an initial plot thread developed for but dropped from the episode . "We developed a whole story about how we were going to come into a war with the Klingons," detailed Michael Piller. (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 191)

A poetic line of dialogue concerning the Klingons (and explaining why Worf never gazed at the stars while in Ten Forward, unlike many of his crewmates) was similarly excised from . Ron Moore, who wrote the line, recalled, "Worf said something about [...] 'To look at the naked stars is to ask them questions, and Klingons do not ask questions for which there will be no answers; we make the stars ask questions of us." ("Yesterday's Enterprise" audio commentary, TNG Season 3 Blu-ray)

"Sins of the Father" 
One of the most definitive episodes for the Klingons is . Ronald D. Moore noted, "It was kind of a landmark show in terms of portraying their culture." () The installment gave an insight, for the first time, into how Klingons behaved on their homeworld. The story basically came about as a combination of two Klingon-centric scripts, "Our Brother's Keeper" by Beth Woods and "Brother to Dragons" by Drew Deighan, though Moore also found himself assigned to help develop the episode. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) He noted, "This was the first time I really concentrated on the Klingons as a whole." ()

When Ron Moore joined the TNG writing staff and began working on "Sins of the Father", Michael Piller – who was by now running the writing staff – asked Moore to write him a Klingon-defining memo. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray; ) "As part of the [episode's] development process," recounted Moore, "he said, 'Tell me what you know about the Klingons. Write up something that tells me about their culture." () This was because – as Piller wasn't a Star Trek fan – he was attempting to understand who the Klingons were. Since Moore was a fan, he had his own opinions about the nature of the Klingons. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) "I just went upstairs to my office and pounded out my take on the Klingons," he remembered. "I felt I was starting with a blank page [....] I really did feel that there was a great deal that had yet to be explored, and that there was a lot of room to play around with." ()

Indeed, the fact that very little had been firmly established about the Klingons, canonically, provided Ron Moore with a lot of creative freedom to invent facets of their culture in the memo, so he wrote his own personal ideas regarding the species into the document. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) For example, there was no canonical information about the workings of Klingon politics. Moore therefore invented the Klingon High Council and set up the ground rules of Klingon government. ()

Though Ron Moore didn't feel bound to the past, his thoughts about the Klingons did have some televisual and literary roots. "I took what I had seen in the original series as a jumping-off point," he noted. () Apart from a couple of key installments that previously developed the Klingons in TNG, Moore also recalled the few details about them that had been set up; "Certain things about their culture having, sort of, honor-bound traditions were sort of established." ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) The experience of having written "The Bonding" was also an influence on the document. ("The Bonding" audio commentary, TNG Season 3 Blu-ray) Much of the memo's content was inspired by literature, with The Final Reflection serving as the primary influence. In general terms involving Houses and conflicts between them, the fictional universe of , created by Frank Herbert, was very influential too. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) Two historical societies, the Samurai and Vikings, served as other inspirations, Moore perceiving about Klingon culture, "There was the calm, elegant reserve associated with the Samurai but there was the 'party-down' like the Vikings." () Additionally, he said of the Klingons, "They had these real intricate codes of honor and poetry, like the Samurai. They were also like the Vikings; they were big, brawling, larger than life, they liked to drink and sing big songs like the Vikings, or at least our conception of the Vikings. That was where I began with the culture. The irony was that I wrote them more like the Romulans had been in the original series [as a very honorable warrior caste who had codes of ethics]." ()

There were two main elements which were decidedly not influential on Ron Moore's writing of the memo about the Klingons, the first being the reference book The Worlds of the Federation. "I hated the chapter on Klingons in that," he stated, "so I went out of my way to do everything the opposite of what it said!" The second was the use of the Klingons as metaphorical representations of the Russians. "I stopped thinking of the Klingons as the Cold War adversary," he explained. "I didn't think it fit [....] The place where the Russians were when I was doing the Klingon shows just wasn't as relevant any more. The Wall had fallen, and it was all about the collapse of this empire, and what they were going to do internally, and how do they become a democracy. I didn't want to take the Klingons down that road, because it would have essentially defanged them and I liked keeping them more dangerous [....] I wanted the Klingons to be this long-running Empire with a long, glorious history, [whose politics had gone on for a few thousand years] and whoever is up and whoever is down is just one more chapter." ()

Entitled "Klingon History and Culture: A Brief Overview" and running two pages long, Ron Moore's descriptive memo about the Klingons began with a description of the Klingon Empire, outlining that the planets therein enjoyed "many advantages and benefits of their association with the Klingons." The memo went on to say, "The Klingons are not evil, tyrannical pirates bent only on pillage and plunder. They have a strict, almost unyielding code of ethics and honor and take their responsibilities as rulers seriously." Following a description of the Klingon homeworld, the memo continued by saying, "Klingon society could most closely be compared to that of Sparta or feudal Japan." A description of the Klingon Empire's political system followed, involving the High Council and establishing that there was an Emperor. The document continued, "Klingons have a very complex and highly developed code of conduct, involving almost every aspect of their lives. Their sense of honor and integrity is integral to their very being." The text then detailed Klingon Houses and the high importance with which Klingons held them, before stating, "Strangers must prove their worthiness before a Klingon will accept them as an equal. Weakness, either mental or physical, is not tolerated. Klingons are born to be warriors. Time spent in other professions is used only to expand their knowledge and range of skills in preparation for being a warrior. Several of the races they have conquered now serve as the merchants, farmers, traders, machinists, et cetera, of the Empire. Klingons respect courage, strength and cunning, in that order [....] Klingons respect the declared war, the killing stroke, the blood feud, death in the field of battle and clear positions of hostility." ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray)

The names of several characters in "Sins of the Father" were thought up by linguist Marc Okrand. () Something which differentiated the Klingons from the Romulans and the Starfleet crew of the Enterprise was the Klingons' love of ritual, a facet which had already been somewhat explored in episodes such as  and "The Bonding". "It just seemed like that was part of their culture," Ron Moore remembered, explaining why he chose to include it in the installment which became "Sins of the Father". ()

After Ron Moore and W. Reed Moran co-wrote a script that was based on the teleplays for "Our Brother’s Keeper" and "Brother to Dragons" and was entitled "Sins of Our Fathers", Michael Piller wrote a criticizing memo in which he stated, "I [...] feel we haven't adequately defined or explored the Klingon culture." Contrastingly, at another point during the writing of the episode, Piller decided the Klingon ceremonies established in the installment were too numerous, excluding one which Moore later described as "an elaborate sort of a take-off on a Japanese tea ceremony that was sort of a traditional greeting when someone came to your home." ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) Despite Piller's feelings, the ritualistic aspect of the Klingons remained in the episode. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray; ) Personified in the relatively understated portrayal of Chancellor K'mpec (in contrast to the Klingons' tendency for bombastic behavior), Piller was very fond of thinking the Klingons publicized a sense of their culture to outsiders that was not necessarily true within the society and that there were, as Moore phrased it, "the public face of the [Klingons] and then the backstage face of the Klingons." ("Reunion" audio commentary, TNG Season 4 Blu-ray)

Ron Moore envisaged the Klingons as a frequently corrupt society. "That was one of the great contradictions of the Empire; the society is built around a concept of being honorable," he stated, "but those principles are often sacrificed and compromised by people like Duras." ()

The ways in which the Klingons ultimately dealt with Worf's brother, Kurn, changed considerably between the various script drafts of "Sins of the Father", though the Klingons dishonored Worf at the end of all drafts of the script, a plot point whose unresolved quality was then very rare for the series and allowed the installment to become the first part in a Klingon arc. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) Ron Moore fought for the unconcluded nature of the episode. He was initially unsure if the series should produce a Klingon-heavy sequel to "Sins of the Father" but realized, "Whenever we run into a Klingon ship from now on we're forced to deal with it." (Cinefantastique, Vol. 21, No. 2, pp. 45 & 59)

In his role as Kurn, Tony Todd appreciated the nature of the relationship between his own character and Worf. "I loved the battling that went on between Worf and [Kurn]," Todd reminisced. () Because he had a relatively large head, Todd could fit into Michael Dorn's rather large Klingon headpiece. Although there were several members of the House of Mogh, Dorn's headpiece couldn't be used on all occasions, however. Michael Westmore observed, "Michael Dorn's head is so big that nobody else could really wear it [....] Everybody else that has come along has a smaller head and could never wear Worf's head." ()

Although the Klingon makeup remained arduous, Duras actor Patrick Massett was of the belief that it helped found the Klingon characters. "The real clincher is when they stick your teeth in," he revealed. "You have something to bite." ()

Focusing on Klingon politics to such a degree as "Sins of the Father" does involves an element of risk. Observed Ron Moore, "It's really interesting how deep into Klingon politics the show got. I mean, this was a fairly unheard-of thing [....] And it was asking the audience to buy into that and to actually care about that. And Michael [Piller], I remember, was [...] always kind of on-the-fence about it. There were times when Michael Piller thought that was great, it was taking the show in a new direction. Other times, he kind of went, 'You know what? I don't know if the audience is gonna care about whether the Klingon Empire falls into civil war or not." By continually leaning on how the political goings-on had dramatic repercussions for Worf, Moore thought the episode's political machinations were successfully engaging. "You are caught up in the political nature of the story," he expressed. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray)

After completing the script for "Sins of the Father", Ron Moore had no reason to expect he would be requested to write any more Klingon episodes. () The focus on Klingons in "Sins of the Father", however, established him as key to the development of the species. He remembered, "I got tagged with being 'the Margaret Mead of the Klingons' right after I did 'Sins of the Father' for TNG [....] In story meetings, people started talking to me about the Klingons, like I knew them or something." () Moore was regarded as an expert on the Klingons not only because he had written "Sins of the Father" but also due to him having written the memo concerning the species. Even though the writing staffers kept asking him questions about the Klingons, he didn't have all the details about the species worked out. ()

In fact, there was a perception among the TNG staff writers, even with Ron Moore, that the Klingons were somewhat weird aliens. "Whenever we were doing Klingon shows," he recalled, "there would be knife fights, people would challenge each other to duels, and Rick Berman always said, 'How do you guys run a car factory let alone an entire planet like that?' They always seemed a little strange." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 83)

Nonetheless becoming the custodian of Klingon culture, Ron Moore found himself writing the vast majority of Klingon installments for TNG. Each episode he wrote seemed to present him with new opportunity to explore different facets of Klingon culture, elaborating on his original sketchy memo. "Everything that I did, I did for specific episodes," he recalled. "In each episode I would explore this terrain, or I needed to accomplish something that would force me to examine this part of the culture, but I never sat back and tried to develop a master scheme. As a result, there are certain internal contradictions, but I didn't want to sit back and try to come up with a full-blown outline of how the society worked, because I felt that was restrictive and that it wasn't serving the goal of making the show." Although he attempted to keep everything he wrote consistent with previous shows, Moore was careful not to create too many rules for Klingon society. "I seldom went beyond what I needed to do in an episode," he said, "but I'm sure if you actually looked back through the scripts there's probably scenes and lines and references that would influence how you thought about the Klingons that never made it to the final version." ()

TNG Season 4 

The developing Klingon mythology was significantly explored in fourth season installment . "That was really where we began embroidering the larger saga that was sort of developing about the Klingons and Worf," reflected Ron Moore, "and that would lead to the civil war and [fourth season ender] 'Redemption'." ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) Two factors mainly motivated the unusually extreme amount of continuity among the Klingons in "Reunion": the seemingly obvious fact that the writers were going to follow up the story of the Klingons having dishonored and discommendated Worf in "Sins of the Father" and a desire to return the fairly popular character of K'Ehleyr to the series. Furthermore, Klingon traditions such as the Klingon death ritual and turning one's back on someone with the intention of dishonoring them were reused from "Heart of Glory" and "Sins of the Father" respectively. ("Reunion" audio commentary, TNG Season 4 Blu-ray) "By the time we rolled around to 'Reunion', the Klingons were a society that had a lot of ritualistic elements," observed Moore. "That was just something else to keep embroidering on and keep using." ()

Dealing with intense political machinations between core Klingon characters, the genesis of "Reunion" was a story outline and script which had the oft-reused title "What Dreams May Come" and was written by Drew Deighan. This version of the story began with K'Ehleyr and Worf's son arriving on board the Enterprise, after which a Klingon battle cruiser – commanded by Duras – arrived. By the episode's conclusion, a Klingon Civil War broke out, Duras and K'Ehleyr were both killed, followed by some family bonding between Worf and his son. Thomas and Jo Perry adapted this form of the plot into a different outline and a different script draft, which added many of the elements that remain in the episode, such as introducing the ultimately much-seen recurring character of Gowron and naming Worf's child "Alexander." Ron Moore and Brannon Braga used this, to a large degree, as a basis for them to collaboratively write the final draft of the episode's teleplay. By this time, Braga regarded Moore as "an expert" on Klingon mythology, though Moore himself later conceded, "I just made it up as we went along." ("Reunion" audio commentary, TNG Season 4 Blu-ray)

About the same time as he worked on the writing of "Reunion", Ron Moore found that the grand themes explored in such episodes put the Klingons on an epic stage and played to his strengths as a writer, as he was drawn to history and politics. "The Klingons seemed to lend themselves so easily to it [i.e., an epic saga] that it was a good fit," he reasoned. "I could write in these Shakespearean terms of the rise and fall of empires on a very large canvas [extremely akin to] Shakespeare's history plays." And just as with several characters in Shakespeare productions, Moore wanted the Klingons in "Reunion" to be extremely duplicitous. "The whole Klingon epic at that point," he continued, "was just soaked in intrigue and conspiracy and cross and double-cross [....] It made it more interesting if it wasn't quite so clear whose side was right." ()

The notion of the Klingons progressively poisoning K'mpec was an idea which Michael Piller liked and which remained in all drafts of the teleplay for "Reunion". Also, the staff writers believed it necessary that Duras and K'Ehleyr die in the outing. Though the episode originally included the Klingon homeworld and more scenes on board the Klingon battle cruiser than eventually ended up in the installment, the Klingon scenes were edited so much that Piller wrote a note to Ron Moore, specifying that only one Klingon set was permitted in the script. However, this was not to be and Denise Okuda once commented that the Klingon settings which were featured were "cool ships." ("Reunion" audio commentary, TNG Season 4 Blu-ray)

Though obviously belonging to Worf's family, a smaller prosthetic headpiece was used for Alexander when Jon Steuer played him in "Reunion". The crafting of a miniature version of Worf's cranial ridges was due to the fact Steuer had a smaller head than Michael Dorn's. () For Gowron, the makeup artists never had to create a mold for actor Robert O'Reilly, instead simply measuring his head by eye and using one of the standard skull molds to model his cranial ridges on. However, O'Reilly did need to have a dental mold made for them to craft his artificial teeth. (Cinefantastique, Vol. 27, No. 4/5, pp. 107-108)

Production staffers such as Doug Drexler tried to help performers playing Klingons – for instance, Robert O'Reilly – with their portrayal. "There were actors who came in to play Klingons who had never seen the show," said Drexler. "So it was part of the job, as the makeup artist is applying their makeup, to help the actor find the proper mindset." (Star Trek: The Next Generation 365, p. 212) O'Reilly himself postulated, "As soon as you become the Klingon leader, you become the antagonist [....] As soon as you're the leader, you immediately change, like any leader does. It was inevitable." ()

At first, Robert O'Reilly rationalized meticulously about Klingon anatomical details. "When I started doing Gowron, I picked apart every physicality," he explained, "and worked on it separately before integrating it [....] I [even] thought about how the Klingon eye might work within the rest of the body." ()

Robert O'Reilly noticed the Klingons didn't have overly complex dialogue, aside from Klingonese. "If you watch Klingons, we rarely have the [technobabble] in our dialogues," he pointed out, "which is a great relief." (Cinefantastique, Vol. 27, No. 4/5, 108)

Although he established in "Redemption" that women may not serve on the Klingon High Council, Ron Moore didn't immediately realize the repercussions for females. "Even then," he recalled, "I didn't think it through and realize this was a very large sociological point about the Klingons; it was strictly a plot point [....] I wasn't trying to imply that they [Klingon females] were second tier citizens at all." () Moore elaborated, "Not letting women on the High Council was done for a specific reason [...] in the 'Redemption' arc because I'd needed a plot device to make the story work." () The change, which contrasted with Gowron offering a seat on the High Council to K'Ehleyr in "Reunion", was also made because Moore wanted to differentiate the Klingons from the Federation and the Romulans. He imagined the Klingons as "a traditionally patriarchal society," with many aspects of that having disappeared over time, and pointed out, "It's an alien society with alien values and we shouldn't be able to identify with all aspects of their culture." 

The appearances of so many Klingons on TNG influenced the show's makeup department to devise new ways of dealing with the consequent makeup demands. "In the case of a story like 'Redemption', which had a large cast of Klingon characters, we had to develop a series of shortcuts to save time," explained Michael Westmore. "Instead of making a cast of each actor's head for example, I would measure their head when they walked in the door. If their head size was close to that of a pre-existing mold, we would create our new design on an available head mold. Quite often, if we had two actors with similarly-sized heads, I would sculpt the first forehead design, and after taking a mold from it, the clay sculpture would still be intact. This would eliminate the need for 'basing it up'; the process of putting the clay on the mold." Thanks to this time-saving measure, Westmore was able to immediately begin redesigning a new bone structure for the second Klingon. Rather than spending a whole day on the new sculpture, he could re-sculpt the second head design in three or four hours. (Star Trek: The Next Generation Makeup FX Journal, p. 29)

In season five opener , Ron Moore wrote a Klingon nightclub scene involving a party with two warring sides and Klingons socializing together regardless of their affiliation. "It's like the old Warner Brothers cartoon with the sheepdog and the coyote," Moore expressed. "They're at each other all day, then the whistle blows, and they punch their card and go home together. I thought, well, Klingons are sort of like that too [....] I just loved that, I thought it was a very odd, not Human society." () For the same scene, Director David Carson originated some new forms of Klingon actions. "Rick Berman encouraged me to invent new ways of behaving," Carson remembered, "which is why they banged their heads together as a game; or arm wrestling with pointed daggers attached to their wrists. It was totally Klingon and it's an interesting world to work in." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 227) The interaction between Klingons in "Redemption II" also included a battle between Gowron and a Klingon challenger named Kulge. Robert O'Reilly described the conflict as "a fairly short fight." (Cinefantastique, Vol. 27, No. 4/5, p. 108) Shortly following the making of the "Redemption" two-parter, Berman himself stated, "We've played out our Klingon political trilogy to a point where we can take a rest for a while." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 227)

Robert O'Reilly believes that, from "Redemption II" onwards, the Klingons developed a sense of humor. "I think the writers started edging towards that," reflected the actor. "They were also scared of it. They didn’t want to go too far. Eventually I think most of the writers went, 'Yeah, we can go there.' From that moment on, I think Klingons could have a sense of humor."  In a  interview, however, O'Reilly stated, "I've noticed that most Klingons don't have a sense of humor and I have always felt that was due to a choice of playing it too much one-way." () The actor later detailed, "A Klingon having a sense of humor hadn't really been done at that point. The writers saw that it would be fun." ()

Star Trek VI 
Three days after Frank Mancuso – who was President of Paramount Pictures at the time – asked Leonard Nimoy for help in making Star Trek VI, Nimoy devised an idea for the film's plot which was centered on the Klingons. (Star Trek Movie Memories, hardback ed., pp. 277-278) He gave much consideration to how the Klingons were similar to the Communists. Influenced by the contemporaneous crumbling of both the Soviet Union (which included Russia) and its border which was the Berlin Wall, Nimoy chose to represent the Klingons as encountering analogous circumstances. "Realizing that over the 25 year history of Star Trek, the Klingons have been the constant foe of the Federation, much like the Russians and Communists were to democracy, I wondered how we could translate these contemporary world affairs into an adventure with the Klingons," stated Nimoy. "I thought it was an ideal way for us to have our closure too, because the Klingons for us have always been the Communist Block, the Evil Empire. It just made sense to do that story." (The Making of the Trek Films, UK 3rd ed., p. 100) Nimoy imagined that, unless they agreed on a treaty with the Federation, the desperate Klingons would be akin to "East Berliners streaming over the places where the [Berlin] Wall used to be." (The View from the Bridge; "")

Once he conceived the Klingon-centric story idea for Star Trek VI, Leonard Nimoy told Frank Mancuso the concept. "I came back to Mancuso and said, 'Okay, here's my idea. The Klingons have this terrible problem. Their economy is screwed up just like the Russians. We've always used the Klingons as our analogy for the Communist Bloc, and now, for the first time, they'll have to reach out for help and admit they have a problem. The crew of the Enterprise will try to save them." (Star Trek Movie Memories, hardback ed., p. 278)

During a meeting which Paramount Vice President of Production Teddy Zee had with Leonard Nimoy and writing duo Mark Rosenthal and Lawrence Konner, Zee veered from Nimoy's plan of focusing the sixth movie on the Klingons by instead proposing the story should be about Romulans. Nimoy maintained that the plot revolve around relations with the Klingons, stipulating, "This is not just another Star Trek, this is the close of our hostile relationship with the Klingons at the end of twenty-five years." (Star Trek Movie Memories, hardback ed., p. 279) Rosenthal attested, "We had two meetings with Leonard and Teddy, where we said the film should be about a peace with the Klingons, and that it would be a nice parallel to reality." The main concern which Rosenthal and Konner had – while trying to help write the film – was that very few details about the Klingon Empire had previously been established. In Rosenthal and Konner's version of the plot, the Klingons arrested Kirk when he was turned over to them by Sulu, though this arrangement actually had secretly been set up by the Federation President, so Kirk didn't resist the Klingons arresting him. The writing duo planned to establish much about Klingon society in the story. "We discussed the fact that the Klingons are this aggressive race," remembered Rosenthal. "Originally they supposedly had this reptilian background. In regards to this whole thing about Kirk and his search to uncover the conspiracy behind the assassination....we originally came upon more primitive Klingon tribes who had an almost religious representation for the Klingons the way that they do for the United States in Dances With Wolves. They would be much more primitive and violent. We were going to do a whole thing on the anthropology of the Klingons, but all of that was dropped because it would have been too expensive." (The Making of the Trek Films, UK 3rd ed., pp. 99, 100, 106 & 104)

The Klingons were thought about in great detail by Leonard Nimoy and Director Nicholas Meyer when they had an initial discussion about Star Trek VI, on Cape Cod beach. Meyer recalled, "Leonard asked me, 'What would happen if some terrible thing happened to the Klingons and they tried to make peace?' We talked about that for a long time." (Star Trek Movie Memories, p. 281)

The way the Klingons in Star Trek VI were used to reflect relevant issues within Human society was extremely valued by some members of the film's creative personnel, including Denny Martin Flinn. "So when Leonard [Nimoy] came up with the idea that the Klingons could stand in for the Russians and we could deal with the end of the Cold War," said Flinn, "we were home free in terms of fundamentals that we knew worked." (Cinefantastique, Vol. 22, No. 5, p. 46) Gene Roddenberry was likewise enthusiastic about the concept of forging peaceful relations with the Klingons, as it was a stepping stone to the future of a Klingon serving in the Federation on TNG. "He was very intrigued with the idea that we would be exploring the relationship with the Klingons," reported Nimoy. "He was concerned in this particular story about the prejudice question [...] [but] by and large, he was quite taken with the idea of a Klingon detente." (The Making of the Trek Films, UK 3rd ed., p. 101) On the other hand, Roddenberry wasn't completely happy with how the species was portrayed in that situation. In fact, Richard Arnold remembered, "Gene was really bothered by the Klingons in VI [....] [They] were, in his words, 'too civilized, too decent, too much of the good guys in the story.' [....] [The Klingon detente] was not the way Gene would have handled it. He would have reversed it, he would have had the Klingons being the ones who couldn't handle the peace, with the Federation saying, 'Come on, let's try and work this out." (Star Trek Movie Memories, hardback ed., p. 289)

While co-writing the script of Star Trek VI with Nicholas Meyer, Denny Martin Flinn felt free to write about the Klingons as he saw fit – because he didn't have a detailed knowledge of Star Trek before joining the production – and to make any necessary changes afterwards. He reflected, "There was an attitude on my part that if somebody in the first draft says Klingons don't eat with their left hand, they eat with their right, I'll just change it." (The Making of the Trek Films, UK 3rd ed., pp. 101-102)

Leonard Nimoy wanted to use Star Trek VI to explore Klingons and their culture. "It seemed to me that this movie presented us with a perfect opportunity" to do so, he said in retrospect. The depiction of the Klingons in Nicholas Meyer's and Denny Martin Flinn's first draft of the film's screenplay, however, frustrated Nimoy. "The story never explored the Klingon culture the way I'd hoped it would [....] I was hoping for greater insight into the Klingons." (I Am Spock) Nimoy hoped, in specific, that the movie would provide some important insight into why the Klingons had "always been so angry, such nasty, vicious murderers." Nimoy wanted the insightful knowledge to be an intellectually transformational force, changing the thinking of Kirk and the audience. On the other hand, Meyer was never comfortable with that notion and, though the writing team attempted to make it work, it simply "just never came to be," in Nimoy's words. (Star Trek Movie Memories, hardback ed., pp. 287-288)

The Klingons in Star Trek VI were additionally influenced by other races than merely the Soviets. Nicholas Meyer thought up one of these ideas, bearing in mind a Klingon courtroom scene from the film. Recounted Nilo Rodis, "He said, 'The Klingons are kind of like Romans throwing Christians to the lions." This concept went on to inspire the design of the courtroom itself. Thousands of Klingons were initially imagined as being inside Star Trek VIs Klingon courtroom. However, this quantity had to eventually be lessened because the production was limited to including only sixty-five background performers selected to play Klingons. (Cinefantastique, Vol. 22, No. 5, p. 55) The references to Klingons in Star Trek VI also incorporated racial insults very similar to real-world anti-black statements. (The View from the Bridge; ": Prep–Casting")

As for the possible ancestry of the Klingons, Gregory Jein – who served as props master on Star Trek V as well as on Star Trek VI – theorized that they developed from an underwater species. "My philosophy is that the Klingons came out of the sea originally," he mused, "and the sea was their basic cultural heritage." Jein took inspiration from this belief when crafting many of the Klingon props from Star Trek VI. He observed, "Most of the Klingon stuff I designed had that quasi-organic look [....] A lot of their props have a biomorphic shape to them." (The Making of the Trek Films, UK 3rd ed., p. 129)

Nicholas Meyer wanted Star Trek VI to show Klingons interacting with their disruptors more than the species had ever been depicted doing so before. "On this film, Nick Meyer decided he wanted to show the Klingons drawing their phasers out of their holsters," Greg Jein pointed out. (The Making of the Trek Films, UK 3rd ed., p. 129)

For Star Trek VI, Richard Snell was made responsible for designing and fabricating all the Klingon make-ups, enormous numbers of which were needed. In fact, more Klingons are featured in Star Trek VI than those in the franchise's earlier films combined. The task of creating sixty-six suitably realistic Klingon make-ups was at first deemed too much of a workload for the movie's limited make-up department to take on, in the times allotted. "Fortunately, Paramount was gracious enough to say, 'Do what you have to do. If you need 66 Klingons, then hire accordingly' and we did," reflected Make-Up Supervisor Michael J. Mills. (Cinefantastique, Vol. 22, No. 5, p. 33) Klingon appliances were produced by a staff employed by Snell's makeup lab. (Cinefex, No. 49, p. 44) Noted Snell, "On certain days, we had upwards of 75 to 80 makeup people working." (Cinefantastique, Vol. 22, No. 5, p. 33)

Richard Snell was relieved that, in Star Trek VI, Nicholas Meyer gave him leeway to design the Klingons as slightly more diverse and grotesque than they had been in previous films. (Cinefantastique, Vol. 22, No. 5, p. 33) Regarding the variety abundant in the movie's depiction of the species, Michael J. Mills explained, "Since the Klingons were to play such a major part in the proceedings, the director wanted them to be as believable as possible. He wanted the audience to watch the actors' faces and not be distracted by the makeups. So every one had to be a custom job – which translated out to be about three-and-a-half hours. Richard Snell did a great job of coming up with all sorts of different designs for the Klingons, and we used the newest techniques and glues and paints for the applications – which was important since these characters were being seen face to face with the principal actors playing humans. The appliances had to be very thin in order to allow the expressions on our actors to come through and read clearly." (Cinefex, No. 49, p. 45) Offered Snell, "We had about 18 different designs for all the speaking roles. For the courtroom sequence, we had another 30 'A' makeups, 40 of the 'B' foam latex background mask makeups which still required makeup artists because they blended around the eyes, and 50 over-the-head polyurethane plastic Klingon masks for the far background ones. We'd then paint and hair each of those background Klingons differently. We had a wide diversity of styles, from very sedate to wild, heavy, bony plates. All told, we delivered over 300 Klingon pieces." (Cinefantastique, Vol. 22, No. 5, p. 33) Elements such as hairstyles and jewelery made the Klingons even more physically diverse. "Ron Pipes, working with Richard Snell, did a lot of work designing the wigs, which played a substantial role in making the characters look more believable," remembered Mills. "Our hairstylist, Jan Alexander, was instrumental in coming up with various braids and jewelry which suggested a tribal people with a whole heritage and history behind them." (Cinefex, No. 49, pp. 42, 44 & 45)

The Klingon makeups in Star Trek VI had to work well in sync with the lighting. Cinematographer Hiro Narita offered, "Sometimes in a warm ambient [light], the Klingons looked too red, so the makeup people had to adjust it or I'd adjust my lighting here and there." (The Making of the Trek Films, UK 3rd ed., p. 116) This was despite the fact that the Klingons had, by now, a red color scheme. It was used for ship interiors in Star Trek VI as well as in earlier films and briefcases in the sixth film, though not for a judge's gavel in the same movie. (The Making of the Trek Films, UK 3rd ed., pp. 116, 129 & 128)

Leonard Nimoy and Nicholas Meyer agreed it was logical for the actors who played Gorkon and , two Klingon characters important to the story of Star Trek VI, to be name actors of talent and presence. (The View from the Bridge; ": Prep–Casting") "All I knew about Klingons was that they weren't very nice," admitted Gorkon actor David Warner. "What the attraction of this was was that he was the bridge between Klingons."  Meyer met with Whoopi Goldberg to discuss casting her as a Klingon princess in the film but Nimoy vetoed this idea. (The View from the Bridge; ": Prep–Casting")

The philosophy behind how Klingons relate to their spacecraft developed during the creation of Star Trek VI. William George recalled, "We did some research into military costuming, and came up with the concept that when these ships return victorious from battle, the Klingons build some sort of epaulet onto their wings or paint a new stripe on." (The Making of the Trek Films, UK 3rd ed., p. 119)

Answering a casting call for Klingon extras in the Spring of , TNG Pre-Production Associate Eric A. Stillwell and Trent Christopher Ganino, who co-wrote the story for "Yesterday's Enterprise" with Stillwell, signed up to be Klingon extras for Star Trek VI, as Nicholas Meyer required a roomful of Klingons for the film's trial scene. () "Trent got to be one of the three Klingon judges," Stillwell explained, "and I was one of the non-descript Klingons in the rafters."  Stillwell continued, "I soon learned that being a Klingon is no easy task [....] Unlike Klingons with speaking roles, Klingon extras don't wear perfectly sculptured prosthetics with carefully crafted make-up applications. Instead, the make-up staff painted dark circles around my eyes to hide the eye holes cut into the heavy rubber mask I would wear over my head. With my rubber neck tucked tightly under the collar of my costume, it was impossible to remove the mask except during lunch breaks and the end of the day." As the trial scene was scheduled to take two 16-hour days to film, the extras stood in the courtroom set for hours on end. They encountered problems with their heavy rubber masks, because the performers could hardly breath through the masks' tiny nose holes. The conditions on the set were also difficult, as the camera lights heightened temperatures inside the masks to almost unbearable degrees and visibility was hampered by smoke pumped into the room. "The sweat dripping from our rubber eye holes made us look like a bunch of bawling bad guys," related Stillwell. As the first day wore on, an increasing number of the performers seemed to disappear into adjacent sets, which were to be used for depicting Kronos One and were coolly heated as well as darkly lit. On the second day, Stillwell had the forethought to use a turkey baster to pry open the rubber lips of his mask, whereas an assistant director found tampons for all the other extras to use as breathing tubes. Stillwell concluded, "Nicholas Meyer had to remind us to remove the tubes from our rubber lips whenever the camera rolled, least we appear on film as a bunch of Klingons with serious nicotine habits!" ()

The illusion of hordes of Klingons in Star Trek VIs courtroom scene was heightened by the Klingon-playing actors in the audience appearing as merely silhouettes in seats, due to the darkness of the courtroom. (The Making of the Trek Films, UK 3rd ed., p. 116) Though only three rows of Klingon-playing extras were included in the scene, the existence of many more Klingons on multiple higher tiers was purposefully implied in the film, such as by repeatedly showing a matte painting that provided an overview of the entire hall. Production Designer Herman Zimmerman remarked, "[It] will convince the audience that all those Klingons are really there." (Cinefantastique, Vol. 22, No. 5, p. 55)

For a fight sequence involving Kirk and an alien clashing on Rura Penthe, twenty extras playing Klingon guards took positions on high catwalks above the floor of the set in which the conflict was to be staged. During a rehearsal of the scuffle, the Klingon-playing background performers began chanting a well-known song that serves as background music for a battle between Kirk and Spock in . After about twelve bars of the music, the intoning Klingon extras were joined in the song by the rest of the alien-portraying performers as well as the production crew. ()

Although the creators of Star Trek VI feared they were being too obvious in portraying the Klingons metaphorically, the creative team likely needn't have worried. After Star Trek VI went on general release, Nicholas Meyer explained the allegorical nature of the film's Klingons to his dentist, who had seen and enjoyed the film but had not realized its metaphorical aspects. (The View from the Bridge; ": Endings")

TNG Season 5 
As they wanted to have an older actor play Worf's son Alexander in , the TNG writing staff decided that Klingon children rapidly advance. Reflected Ron Moore, "[We] just told ourselves that, 'Well, Klingon kids grow up really fast." ("Reunion" audio commentary, TNG Season 4 Blu-ray) After the role of Alexander was recast with Brian Bonsall now playing him, Bonsall wore the same miniaturized Klingon headpiece as Jon Steuer had worn. "As the character grew he kept stretching that one out," commented Michael Westmore, "until he finally outgrew it to the point where we had to go to [...] [a] new one." ()

Helping give the Klingons a grand scale was the saga of Kahless, as Ron Moore peppered references to him into various episodes. "I just decided to [...] create the Klingons' own specific take on mythology. I thought, 'OK, what are the values that are important to the Klingons, and how would those values be reflected in the myths and tales that they tell each other as examples of good, of morality, and of greatness in their epic sagas?" ()

By the end of TNG's fifth season, Michael Westmore had most likely sculpted more than thirty different Klingon head designs. He said at the time, "The process of casting the actor's head, making a mold from it, and sculpting the elaborate bone structure, generally takes about two days." (Star Trek: The Next Generation Makeup FX Journal, p. 29)

Even though the Klingons have played an integral part in all incarnations of Star Trek, the motivations behind the species were perhaps most prolifically explored in . () That series featured Klingons as early as its second episode, , in which the Duras sisters reappear. However, regular appearances of the species on DS9 were not foreseen when the series was invented. "We realized that we certainly couldn't have the Klingons as bad guys," said Rick Berman. (Star Trek - Where No One Has Gone Before, paperback ed., p. 154)

After Brannon Braga and Ron Moore wrote the teleplay for TNG Season 6 installment , a Klingon-centered subplot in the episode, featuring some disagreeable Klingons being accused of murder, was thought successful by the two writers. "The Klingon story is the red herring and that's fun," commented Braga. Moore concurred, "I thought it was a nice little runner. I didn't want to make that any bigger than it was. But in the final product, it was one of the more intriguing things. I never thought it would be, but it was just a cool little C story." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 269)

Later TNG and early DS9 
Although the next major Klingon TNG story after the "Redemption" two-parter was  and , Ron Moore, for once, didn't write the story. () Though Brannon Braga and René Echevarria are credited with writing "Birthright, Part I" and "Birthright, Part II" respectively, the two-parter's depiction of Klingons was additionally influenced by Michael Piller. Having recently seen the film Malcolm X, he imagined the Klingons in the "Birthright" duology as metaphors for black people. (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 274; ) Moore was happy for the Klingons not to be developed exclusively by him. "That was good, because it [...] gave a chance to René and everybody else to kind of embroider on the Empire and to bring new things into it, so that later, when I came back and did other Klingon shows, I had more material to work with," said Moore. "I think that the singing in 'Birthright' is something I wouldn't have thought of." () The writing staff put a lot of effort into trying to boost the likeability of the story's Klingons. () Meanwhile, Klingon mysticism inspired a B story in "Birthright, Part I", which involved Data dreaming. "It came from the Klingons sort of having a mystical, mythical, spiritual side," noted Jeri Taylor. (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 273)

Michael Dorn was happy with how Klingons are portrayed in the "Birthright" two-parter, feeling particularly that the pair of episodes showed the Klingon mythology would "never go dry" and would instead "just go on and on." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 274) For timing reasons, though, multiple deleted scenes involving Klingons were taken out of "Birthright, Part II". (TNG Season 6 Blu-ray special features)

Both Richard Herd and Cristine Rose – who played L'Kor and Gi'ral respectively, in the "Birthright" two-parter – auditioned to play their individual Klingon characters and thought of those roles as classic.   As for preparing to portray a Klingon warrior, Herd remarked, "There's a certain way you have to carry yourself. You have to really be able to project the violence and the anger [....] All you have to do is think of the Spartans. They say, 'They'd rather have you come home dead on your shield than come home a coward." Before playing L'Kor, Herd knew people who had played other Klingons.  However, there was apparently no-one who helped Rose adopt a Klingon persona, she later lamenting, "Alas, I don't remember anyone specifically coaching me on Klingonisms." Rose also endured heavy make-up for her Klingon role. "Before they ever applied any makeup at all I had to go in and have a plaster cast taken of my face, with straws in my nostrils so I could breathe. They also made a mold of my mouth to create Klingon teeth," she reported. "If memory serves -- and it often doesn't -- the first day of filming it took six hours to bring it all together. I was blessed to have June Westmore as my makeup artist. After the first day, it took less time, because the look had been created." Although Rose found neither the makeup nor hair changed her portrayal, the Klingon teeth took her some time to get used to, which was difficult for her to do in the couple of days she had in the part. 

The DS9 Season 1 installment  was originally to have featured a Klingon outlaw, a member of a criminal syndicate. The unlawful Klingon was written out of the episode when the assortment of criminals instead became a group of Ferengi. ()

Like Cristine Rose in the "Birthright" two-parter, Tricia O'Neil, who portrayed Kurak in the TNG episode , had difficulty with the Klingon makeup, though seeing it gave her great support in adopting her character's Klingon persona. Similarly to Richard Herd, O'Neil had a knowledge of the Klingons before appearing as one on TNG. 

Use of the Klingons in  enabled Ron Moore, much to his delight, to write an episode about religion. "That was kind of a forbidden topic, basically, in Gene [Roddenberry]'s universe, but with the Klingons, you could go there," Moore reflected. Using Kahless as an allegory for Jesus Christ, Moore wrote the installment as a way of speculating about how the Klingons might react to the return of such a figure. "There was something fascinating to me," he admitted, "about the idea about, you know, if you could clone Jesus and brought him back today, how would people treat him and how would it affect their faith, how would it affect politics." ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray) Owing to the mythical tales surrounding Kahless, Moore was able to make sense of some of the more puzzling elements of Klingon culture. He said, "I was trying to bond the society together and explain things." For instance, Moore wrote about the forging of the first bat'leth, the Sword of Kahless, as a way to reason out why Klingons carry bat'leths. "If I'd sat down at the beginning and tried to create the entire Empire and the entire society, I never would have come up with stuff like that. Those kind of connections just would not have been formed," reasoned Moore. "It was only as I was going through story and writing characters for specific episodes that these connections were just naturally forming [....] I really preferred working that way." In addition, by using the myths of Kahless, Moore made the Klingons seem slightly more sensible, such as by choosing to illustrate that even a Klingon knows it is folly to try to make the wind respect oneself by fighting against it. "The danger was that the audience would start to think of the Klingons as just crazy berserkers. They had to have a brain; there has to be a limit to how suicidal they are, or the entire race would just self-implode [....] I've tried to play that over the years [....] I wanted to pull them back a little bit, and I wanted it to come from Kahless." ()

Of course, many Klingon characters appear in "Rightful Heir". "There were all of these wonderful actors in it, all these new characters [....] The other Klingons were more heavily featured [than Gowron]," observed Robert O'Reilly. () "Rightful Heir" also features a fight between Kahless and Gowron which, in contrast to the skirmish between Gowron and Kulge in "Redemption II", O'Reilly referred to as "a much more complex fight." (Cinefantastique, Vol. 27, No. 4/5, p. 108)

Though installing the clone of Kahless as a kind of honorary Klingon Emperor at the end of "Rightful Heir" could have had major repercussions for the Klingons, the final Klingon show which Ron Moore wrote for TNG was "Rightful Heir". () "I had found a lot to do with them," he noted, "but at the same time, TNG tended to take itself so deadly serious. These guys were ripe for a lot of fun." (Cinefantastique, Vol. 27, No. 4/5, p. 90) Concerning the restrictions of using the Klingons on TNG, Moore also said, "All you could really play with them was the internal politics and the Worf family material." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 101)

The second season DS9 episode  featured Steve Rankin and Tim Russ as Klingon mercenaries Yeto and T'Kar respectively, two Klingon mercenaries hired to steal the  from Jadzia Dax. "We had elevator shoes on in order to look incredibly tall," stated Rankin. "We were hired guns, these Klingons. We were the heavies. So it was interesting because we were scavengers. We were thugs, basically, brought in to rob something. Tim and I thought it was very, very complex, though, because we were stealing this thing out of a woman's body."

"Blood Oath" 
Klingons who were to feature in DS9:  were originally non-specified, aged Klingon acquaintances of Curzon Dax. The storyline, as developed by writer Peter Allan Fields, revolved around them and Jadzia Dax. () Michael Piller noted, "[It] was about an over-the-hill Klingon gang." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 71) The particular Klingons weren't selected until the subject came up in a discussion involving Fields, Piller and Co-Executive Producer Ira Steven Behr. (Star Trek - Where No One Has Gone Before, p. 186) "I asked at the end of the meeting if there were any old Klingons that we could use from the original series," continued Piller, "which would bring a resonance to the story and prove particularly sentimental to certain fans." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 71) Writing staffer Robert Hewitt Wolfe, a fan of the original series, then influenced the plot, suggesting the use of Kor, Koloth and Kang specifically. () Behr recollected, "Robert Wolfe and I were talking and he said as a throw away, 'Too bad we can't use any of the old Klingons.' I went to Michael [Piller] and thought we would have a whole discussion on it, but Michael's eyes just lit up and he said, 'Absolutely, see if we can find them." (Cinefantastique, No. 25, No. 6/Vol. 26, No. 1, p. 107) Fields remembered, "Once he mentioned it, it seemed a natural." () Fields also generally based the Klingon group on American Western prototypes from the film The Magnificent Seven or, to a lesser extent, Japanese prototypes from The Magnificent Sevens movie source material, Seven Samurai. "I wanted each of the old guys to be a specific character," Fields explained. () The writers gave some consideration to killing off the entire triumvirate, but John Colicos persuaded them to let Kor survive the whole episode. (Cinefantastique, Vol. 28, No. 4/5, p. 59; "The Sword of Colicos", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) Jadzia Dax actress Terry Farrell was full of praise for the vivid characterizations of the Klingon characters. () Said Winrich Kolbe, "These guys were real heroes." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 71)

Although the DS9 producers were sure that Klingon-playing actors John Colicos, William Campbell and Michael Ansara were still alive, whether they were still acting was initially unknown to the production staffers. The casting people therefore had to round up the performers to reprise, in "Blood Oath", their individual Klingon roles of Kor, Koloth and Kang respectively. () David Livingston remarked, "It was a thrill to have all three [veteran actors] together." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 72) Peter Allen Fields concurred, "We were quite pleased that all three of these fine actors were willing to reprise their roles." (Star Trek - Where No One Has Gone Before, paperback ed., p. 186) Michael Westmore likewise reminisced, "Meeting Michael Ansara and Bill Campbell and [John Colicos], and the rapport that the three of them had together was great." ("Michael Westmore's Aliens: Season Two", DS9 Season 2 DVD special features) Although Colicos had never met Campbell nor Ansara before all three guest-starred in "Blood Oath", they all got along well. Campbell and Colicos challenged each other for the accolade of most outgoing actor. Colicos noted about his co-stars, "They were great." ()

Behind the scenes of "Blood Oath", the look of the episode's three Klingons was discussed. "We had all those conversations about 'Should they look like the original Klingons?" recalled Ira Steven Behr. The DS9 creative team ultimately opted to keep to current Klingon makeup and assume the trio had always looked that way. () William Campbell at first expected, though, that the characters would look much as they had done, later reflecting, "When I was asked if I was interested in coming back [...] I thought we would be the 'old' Klingons, who didn't evolve with the carbuncle on the head and the various changes that had been done to them. I even said to my wife, 'We'll be the same as we were, only older.' But when I walked in and said to Rick Berman, 'Somebody said we were going to have to put this makeup on, a la Michael Dorn,' he said, 'Well... yeah!" ()

The change in the characters' appearances was puzzling for the other performers too. Recounted John Colicos, "I thought, 'How do I put this look together with what he (Kor) was? How did he mutate into this monstrous lizard?" () Colicos also contemplated, "I find it hard to reconcile the two [alternate concepts of Klingons] [....] It's fair enough for the modern [Klingon] image to have turned into a sort of reptilian mode. On the other hand, what we have now is a huge departure from the original concept." () Michael Ansara remembered, "That was my first question to them [the producers]. Why was Kang all changed now? I tried to understand why the make-up for my Klingon had changed so much, with the putty on the head and all of that." () William Campbell also asked Rick Berman if there was a reason why the Klingons had changed so much. ()

The producers told the returning actors their new look was a natural metamorphosis as part of the Klingon aging process, explaining that Klingons live very long lives, a comment which was perhaps tongue-in-cheek. (; Star Trek: Aliens & Artifacts, p. 128) "They said 'You have to realize that Klingons live to be a hundred years longer than normal and they change gradually," recounted Michael Ansara. "That was the excuse they gave me." () Ansara also recollected, "They told me that the Klingons grow those bumps and ridged foreheads as they get older [...] The reason we Klingons had changed so much, with the bumpy heads and whatnot, is that we Klingons live to be 300 years old." () Recalling Rick Berman's answer for the transformations, William Campbell relayed, "He said, 'Bill, it's about 100 years later [than the original series], and this is the way the Klingons look now, and they've evolved into this." ()

In "Blood Oath", the recycled elements of the Klingon facial appearance included dentures. Talking about his own false teeth, John Colicos stated, "Michael [Westmore] made these in five minutes. He took an impression of my teeth and next morning, there they were, all painted and done [....] After a while, you forget they're in there. They just give a slight sibilance to your speech. But, if you try to eat with them in, you'll be in a terrible mess." ()

However, the design of the three returning Klingons was meant to look somewhat unique. "They wanted to do something different," remembered Michael Westmore, "to give them a different look. So, the hair [...] was permed. So, it had more of a curl instead of the straight type look, and by perming it, they were able to kind of give them larger, bigger hair, so it was more like a mane." The newness had less of an impact on "the Klingon facial look," in Westmore's words. Because the Klingon trio was comprised of relatively old members of the species, the makeup artists subdued their forehead ridges. "Instead of having the big heavy bones like we have on so many of the other ones, even like Worf, [...] the foreheads were much flatter," Westmore explained. "They had a lot of ornamentation to them, but it wasn't the boldness that we have on so many of the other Klingons." ("Michael Westmore's Aliens: Season Two", DS9 Season 2 DVD special features)

John Colicos had his own ideas about the then-modern Klingons, including those in "Blood Oath" specifically. "I don't know how you could equate Klingons with what's going on in the world today," he admitted. "I think the intention was to make them like samurai. That hairdo they gave them is very much a samurai hairdo. A lot of the fight sequences, the moves with the bat'telh, are very much taken out of the Asian martial arts [....] It's very romantic you know, these three old guys, the Klingon over-the-hill gang." ()

Michael Westmore had first-hand experience of witnessing the trio of actors have their Klingon makeup applied and become accustomed to it. "You know, they'd come in, in the morning, and of course, being older, they weren't used to getting up early in the morning," Westmore remembered, "so there was always having to get them coffee, and wake them up, and they'd kind of fall asleep in the chair again [....] It was different for them to get into this makeup, because [...] [the makeup was more elaborate and] the beards were bigger, and they were greyer, and they had curls to them, and the moustaches, they had the Fu Manchu look to them. So, they weren't used to sitting that long to be a Klingon." ("Michael Westmore's Aliens: Season Two", DS9 Season 2 DVD special features) The Klingon makeup in "Blood Oath" caused John Colicos some extreme skin irritation. () He complained, "It was unbelievable getting up at four o'clock in the morning to put on this monstrous makeup [....] This new look took four hours [to put on]." () Michael Ansara agreed, "I preferred the original look because it wasn't so heavy with makeup [....] I didn't expect four hours of makeup in the morning and two hours to take it off at night." () William Campbell, however, described the makeup job for his character of Koloth as requiring a three-hour application process, also expressing that it was discomforting. () As well as saying that the addition of the makeup took three hours, he also concurred that it took two hours to take off at night, commenting, "The hours were horrendously long, but we got through it." () In another interview, Ansara stated it took four hours to remove his makeup late each night, also saying, "Getting in and out of the makeup was difficult, but as an actor, it's part of the business. We know that going into it!" ()

To prepare for directing "Blood Oath" and the Klingon-playing actors therein, Winrich Kolbe didn't watch the original portrayals of the three TOS Klingons. "I thought about it," he admitted, "but I figured, 'What do I need this for?' They don't give me enough information about the characters to develop what I want to do, and I figured the actors knew what they had done, and they did." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 72) Reported Michael Westmore, "Once they hit the stage with their make-up on, it's like all that energy and life came back, and they really enjoyed themselves [....] They were troupers and, you know, jumped in, had a good time." ("Michael Westmore's Aliens: Season Two", DS9 Season 2 DVD special features) In agreement, Terry Farrell remarked, "Wow! Those guys wouldn't give in for a second. They just went for those hours, and you could just tell it was hard for them to do all those hours with all that makeup and hair, but they didn't complain once. They really enjoyed it, and it was really exciting [to watch them]." ("Section 31: Hidden File 07", DS9 Season 2 DVD special features)

Multiple production staffers were satisfied with how the Klingon triumvirate is depicted in "Blood Oath". Stated Winrich Kolbe, "They were just wonderful [....] I was, however, a little bit concerned that these guys could do all the physical stuff that was required. I had to convince them to put stunt people into it." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 72) Ira Steven Behr once described the reappearance of the three Klingons as "really interesting." () Michael Okuda commented, "At first, you almost didn't recognize them because they were in heavy Klingon makeup. But [...] having the three original Klingons on the show was magical for everyone." (Star Trek - Where No One Has Gone Before, paperback ed., p. 186)

The trio of Klingons in "Blood Oath" affected members of the species who subsequently appeared. "We've used those foreheads on other characters, a number of times, since then," said Michael Westmore. ("Michael Westmore's Aliens: Season Two", DS9 Season 2 DVD special features)

"Firstborn" 

Ron Moore felt the Klingons in seventh season TNG outing  – as with the members of the species in "Birthright, Part II" – were another example of René Echevarria's different take on the species. Moore commented, "The stuff he did [...] with them [...] [in 'Firstborn'] is very interesting. [In 'Firstborn'] Worf and Alexander celebrate at a Klingon outpost and they have this sort of mock opera singing, heroic fights and re-enactments of things in the streets and banners and this was a whole different cultural flavor to these guys that I hadn't thought of. My take on the Klingons was sort of more Shakespearean with the House of Mogh and that kind of stuff, and the rise and fall of political players. René brings in a much different element which I think serves them well." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 303) Moore also clarified his belief that the Klingon festivities "just never would have occurred to me." ()

Upon portraying a future version of Alexander in "Firstborn", James Sloyan had to wear a smaller prosthetic Klingon headpiece than Michael Dorn. This was because Dorn's head was a lot bigger than Sloyan's, so a new headpiece for Sloyan was sculpted by Michael Westmore. () The duration needed to apply Dorn's makeup as Worf, by the end of TNG's run, was merely an hour. ()

Although Ron Moore had become personally associated with the TNG Klingons, he didn't miss the species when he joined the writing staff of DS9. One of the first episodes he worked on for the latter series was the Klingon-centric, third season outing  (which involves, as the episode title suggests, the unlikely pairing of Quark and Klingons). () As originally pitched by Tom Benko, after Quark accidentally killed a Klingon visitor to Quark's Bar and Quark therefore became known as "Slayer of Klingons", multiple Klingons came aboard DS9, bringing often-associated problems with them. "I really liked it because it gave me a chance to revisit the Klingons, whom I had done so much work with on Next Generation, and play it differently," Moore remembered. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 83) Specifically, the show finally allowed Moore the opportunity to have some comedic "fun" with the Klingons, he having lamented the fact TNG didn't develop them in that way. (Cinefantastique, Vol. 27, No. 4/5, p. 90) As he and other members of the show's writing staff spent time mulling over the story concept which served as the genesis for "The House of Quark", the prospect of using the Klingons in a relatively unusual way appealed to the writers. "We started talking about [...] how it gave us the ability to revisit the Klingons and their culture," reflected Moore, "and do it with some fun and humor [....] The Klingons were ready for some kind of comedy episode, so this was a great opportunity." () Moore wanted to "really [...] have fun with some of the ridiculousness of their whole system." However, not only was it important to him to portray the Klingons as laughable but also to keep them much as they had been established, rather than "making buffoons of them." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 83) "Bringing Quark there and doing that particular storyline gave me a chance to do both," Moore continued. "It could be a fun episode, but one that kept the Klingons true to who they were. I was glad to [portray the Klingons on the species' homeworld] [...] with a different kind of take [though], instead of the Strum-und-Drang that we usually do." (Cinefantastique, Vol. 27, No. 4/5, p. 90) Moore clarified that the installment "really was a way to generally poke fun at the Klingons without doing a parody of them." ()

"The House of Quark" 
For "The House of Quark", Ron Moore personally thought up the visual image of a group of brutish Klingons utterly dumbfounded by something as incoherent to them as a basic accounting system. ( & 172) "I just love the image of them all trying to follow along on the little PADDs," he said, with some amusement. (Cinefantastique, Vol. 27, No. 4/5, p. 90) Robert O'Reilly offered, "Klingons, with money, and computers; well, it wasn't their thing." (Star Trek: The Official Starships Collection, issue 47, p. 11)

The intense focus on the Klingons in "The House of Quark" called for more time than was usual for other installments of DS9, such as for their makeup requirements. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 84) At about this point in the development of Gowron, Robert O'Reilly's Klingon makeup took about three hours to apply, or less than two hours if two makeup people were assigned to him. (Cinefantastique, Vol. 27, No. 4/5, p. 107) Wearing extensive makeup and a heavy Klingon robe himself, Armin Shimerman could easily empathize with the plight of the actors playing Klingons in "The House of Quark". () O'Reilly, however, appreciated the episode for establishing additional facets of the Klingon mythos, noting, "It adds to the on-going revelation of Klingon culture. We learn more about the institution of marriage, inheritance and what really constitutes an honorable death. We even hear a bit about Klingon law and see what [an] upper-middle-class Klingon home is like." ()

From the experience of doing "The House of Quark", Ron Moore learned the Klingons could be shown in a comedic fashion. "Once I had been able to do that I felt, OK, you can have fun with these guys," he recollected. "This is a point where you're saying they are kind of silly; let's enjoy that and laugh at them. Not make them look like fools, but let's not kid ourselves; they do some pretty crazy stuff." ()

By the time the third season of DS9 was over, Ron Moore had found the Klingons were very pleasureable to write about. "Working with the Klingons has given me a lot of enjoyment," he noted. (Cinefantastique, Vol. 27, No. 4/5, p. 90)

Later appearances 

In an interview in the DS9 Season 7 DVD, Robert O'Reilly observed that a long-running joke among actors who have played Klingons is that they do not want to appear in the Star Trek films as, he believes, the only purpose of a Klingon in one of the films was to be killed off. This is true of , in which every Klingon except Worf dies.

After appearing as Duras sisters Lursa and B'Etor in Generations, actresses Barbara March and Gwynyth Walsh expressed some ideas about how they'd like Klingons, especially the females of the species, to further evolve. "Personally," announced Walsh, "I think we need to examine a fully developed mother-child relationship [....] I'd like to see a balancing between the darker side of Klingon nature and the maternal instinct [....] We have yet to learn anything about the differences between male and female Klingon rites-of-passage. Also, I would like to see what Klingon females get to do when they are not adjuncts of males. Do they operate on their own?" Offered March, "Since I portray a female Klingon, I have often wondered about the historical center for these females. What is their purpose on the Homeworld? How do they fit into Klingon society in relation to the violence [....] I think death is complicated whether you are a Klingon warrior or not. So I don't believe it's possible to say that one dies a heroine just because you've been in a battle. That's a very male perspective and I'm not so sure it would be appropriate to assume that such an ethos automatically applies to the sisters. It's for this reason I don't think Klingon females should be developed exactly like the males. The distinctions need to be highlighted. And I'm sure that the female rite-of-passage of death is a little different than the male rite but reflects equally the honor associated with dying a warrior." ()

The Klingons were one alien race which, by the time  was in initial development, had become an extremely familiar element of the Star Trek universe. Deliberately, much less attention was paid to them in Voyager. (Star Trek: Voyager - A Vision of the Future, pp. 155 & 162) Nonetheless, the species remained a part of the series due to the creators of VOY having a fondness for them. "We always felt Klingons gave us such wonderfully rich stories, because they are such an interesting, complex kind of culture," remarked Jeri Taylor. (Cinefantastique, Vol. 27, No. 4/5, p. 54)

After seeing an episode of TNG, Roxann Dawson pitied Michael Dorn for having to wear the extensive Klingon prosthetics, unaware it was her own destiny to wear similar makeup. () Regarding how the Klingon-Human hybrid B'Elanna Torres was invented for Star Trek: Voyager, Jeri Taylor noted, "We always felt Klingons gave us such wonderfully rich stories, because they are such an interesting, complex kind of culture." (Cinefantastique, Vol. 27, No. 4/5, p. 54) However, Dawson didn't even know what a Klingon was before attending her first audition for the role of B'Elanna Torres. () Upon securing that part, Dawson initiated thorough research into the Klingons. "I asked the producers for every pertinent episode which could tell me about Klingons," she explained, "so I watched very closely and I began to read . And because I accumulated a virtual library of Klingon lore, I found myself carrying out massive historical research on the race – even though Klingons are obviously futuristic beings." () The Klingon aspect of the make-up for Torres was initially accentuated, as it contained large teeth, but Dawson managed to ensure she wouldn't have to wear the oversized dental work, by faking an inability to enunciate clearly while wearing them. ()

"The Way of the Warrior" 
The Klingons were brought onto  in its fourth season because Paramount and the show's producers, attempting to overcome slightly slipping ratings in the third season, were trying to appeal to fans of TNG who were not regularly watching DS9. () Ira Steven Behr clarified that the concept of bringing the Klingons back did not originate from Paramount or , who simply wanted a new, not-yet specified element to join the show. (Cinefantastique, Vol. 28, No. 4/5, p. 28) "The first thought we had was to reintroduce the Klingons," remembered Rick Berman, shortly after the announcement that the species was about to return. Ronald D. Moore noted, "Everyone wanted to see more of the Klingons as part of the franchise." ()

After the writers imagined the Vulcans opposing the Federation in DS9 Season 4, the Klingons were instead thought of as doing the same. The identity of the conflicting species was changed because Executive Producer Ira Steven Behr, who suggested the alteration, was inspired by a line of dialogue in , wherein a Founder posing as a Romulan named Lovok says, "After today, the only real threat to us from the Alpha Quadrant are the Klingons and the Federation. And I doubt that either of them will be a threat for much longer." Behr first proposed the change to Ron Moore (who had written the line and the episode containing it), advising Moore, "Maybe it's the Klingons who should break off diplomatic relations. That might have more heat to it." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 100) A few days later, Behr took the idea to Rick Berman. "I didn't give it any push," Behr recalled, "no emotional tone in my voice like I was really behind this a hundred percent, it was just conversation." Immediately upon suggesting the notion, he witnessed   Berman's body language change enormously. (Cinefantastique, Vol. 28, No. 4/5, p. 29) "And Rick said, 'Boing! The Klingons. It's gotta be Klingons," continued Behr. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 100) He also relayed, "Rick said, 'The Klingons – that's the way to go. Everybody loves the Klingons." () Berman himself later explained, "I have always felt that the Klingons were the most accessible bad guys Star Trek has ever had [...] and by taking the Federation/Klingon truce and unraveling it, we were not going to affect the plot lines of the movies or of Voyager, since they are nowhere near an area of space to be affected." () He clarified, "I think the reintroduction of [...] the Klingons into the series was a great idea." (Cinefantastique, Vol. 28, No. 4/5, p. 24) During a meeting which he, Behr and Michael Piller had with market researchers and other people from Paramount, Berman suggested to the officials the idea of establishing the Klingons as a presence on DS9, referring to the concept as something that "excited" the show's production personnel. (Cinefantastique, Vol. 28, No. 4/5, p. 29)

However, Paramount's reaction to the notion of reintroducing the Klingons was at first only lukewarm. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 100) One benefit of reintroducing them as a major adversary of the Federation was that the DS9 writing staff once again had an antagonistic species in the Alpha Quadrant, the Cardassians residing there having apparently become too sympathetic to remain villains. Secondarily, the writers hoped that, by bringing Worf into the series as a regular character, they "would bring all the fans who miss the Klingons." (Star Trek - Where No One Has Gone Before, paperback ed., pp. 200 & 202) With the addition of Worf, Paramount accepted the idea of returning the adversarial Klingons to Star Trek. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 100) Ron Moore noted, "Everyone thought bringing the Klingons back as villains again would energize the series and give it a new direction to go in this year." () He more personally said, "I thought it was a necessary step forward [....] We haven't really seen the Klingons as real villains [....] Ultimately, though, they're just great villains, worthy adversaries and very interesting. I think that's why we brought them back that way." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 101) Making the Klingons antagonists again took inspiration from history, as everyone on the DS9 writing staff was a history buff. The aspect of history which proved especially influential was the fact that allegiances can sometimes quickly be formed and speedily broken apart. In fact, even the notion of using the Klingons to allegorically represent the Russians, from the perspective of the United States, was again employed. "The Russians were our enemies for a long time and now they are our friends, but who knows?" Robert Hewitt Wolfe pondered. "If the political situation in Russia changes they may be our enemies again." (Cinefantastique, Vol. 28, No. 4/5, p. 30)

In fourth season premiere , the Klingons were set up to become recurring villains. "The whole thrust of this episode was to say that the Klingons are here to stay," noted Producer Steve Oster. () Establishing them in such a way, though, was considerably challenging. Ron Moore remembered, "The question was, 'How do we make this transition work? How do we bring the Klingons onto the series for the first time?' Although we'd seen Klingons and interacted with them on DS9, the Cardassians have kind of been our bad guys for a long time. So it became bringing the Klingons back in a plausible way and tying them into Worf." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 105) Despite Moore having spent years devising stories about Klingons, he did not write "The Way of the Warrior", which focused so heavily on the species and was instead written by frequent writing partnership Ira Steven Behr and Robert Hewitt Wolfe. ()

Director James L. Conway was pleased to be able to bring the Klingons back in "The Way of the Warrior". "I liked adding the Klingon presence to everything else that's happening on ST:DS9," he reminisced. "It gives them [the writers] even more places to go in their storytelling." (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 1)

Bringing the Klingons back to the Star Trek franchise in "The Way of the Warrior" required a lot of work in preproduction. The sheer volume of Klingons presented a challenge for the make-up team. ()

Michael Dorn approved of the Klingon developments in "The Way of the Warrior". "Allowing them to be at war again," he observed, "makes the Klingon characters what they were originally created to be." (Star Trek - Where No One Has Gone Before, paperback ed., p. 201) On the other hand, Robert Wolfe remarked, "I wouldn't call the idea retro Star Trek." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 101)

Julian Bashir actor Alexander Siddig likewise supported the return of the Klingons, believing they were one of the most truly worthy Star Trek villains. "The Klingons weren't the be-all, end-all terrifying super force that the Borg were, but they're always a threat," Siddig opined. "They were always there [....] So, I'm happy the Klingons are back and that they're now our neighbors." () Regarding how the species is portrayed in "The Way of the Warrior", Kira Nerys actress Nana Visitor noted, "The Klingons are fun, there's no doubt about it." ()

Robert O'Reilly was aware of DS9 focusing on the Klingons to a great degree. "When I came on to that," he recalled, "it was sort of a nightmare for the show because, for whatever reason, the writers wanted 20 other Klingons with me. So it was a Klingon show, and [....] the Klingons [were] larger than life. It wasn't so individual; it was like a massive army coming behind me."  Contemplating the militaristic stance of the Klingons in "The Way of the Warrior", O'Reilly stated, "For Klingons it's always better to attack than to be in a defensive mode [....] If things get tough, the Klingons will really go to war. They will [meanwhile] be in an attack mode [....] If there's a threat to the Klingon Empire, we just become more aggressive than usual, and the Founders have created a terrible threat. I think that's where the characters are going, and that's why [there's] [...] such a conflict with Worf [and Gowron in 'The Way of the Warrior']." O'Reilly initially wasn't keen on the notion of Gowron and Worf quarrelling, though, until he read the entire script for the episode, which gave him a better understanding of where the arcs of the characters were going and why. The actor was eager to delve into the relationship between the two Klingons in future installments, performing with Michael Dorn, who O'Reilly felt had taught him a lot about the Klingons and portraying a member of the species. "We're a little wacky at times, because, well, because Klingons tend to be a little wacky at times. We don't take it too seriously," admitted O'Reilly. For Klingons, interaction between the genders was generally much rarer, or so thought the actor. "Somehow, the Klingons just don't seem to work with the women on the ship or the space station," he continued. "I don't know the reasons for that. They just keep us Klingons away from the ladies." ()

J.G. Hertzler was swayed from portraying Martok in an understated, Machiavellian way by James Conway and came to the opinion that Gowron was instead intended to channel this character type. () Hertzler once joked that, whereas he had to "wear a lot of make-up" to play Martok, Robert O'Reilly needed no make-up, even for Gowron's trademark bulging eyes. As a self-described "Green Party member and pretty much a left-wing liberal," Herztler believed the DS9 writing staff had a responsibility when it came to portraying the Klingons as violent. "I did mention that to the DS9 writers. But I love the Klingons, and that's who they are." () Hertzler pointed out, "Klingons operate on an extreme level of behavior [....] It takes a certain amount of intellectualization to say, 'War is wrong.' Klingons are not able to do that." ()

Circumstances for the actors who played Klingons in "The Way of the Warrior" were strenuous. On the first day of filming the episode, Klingon-portraying actors on a smoke-filled set, which was used as the 's bridge, had to not only endure wearing uncomfortable, heavy costumes but also extreme heat, as the temperature outside the soundstage was approximately ninety degrees. ()

In "The Way of the Warrior", the action involving the Klingons invading Deep Space 9 was ramped up by James Conway and Stunt Coordinator Dennis Madalone. "It looked like nonstop Klingons everywhere," recollected Madalone, "but it was just four or five guys that we made look like fifty!" () Conway recalled, "I had all these different teams of Klingons beaming into Ops. In fact, I was doubling the stunt guys – you change their moustache and their beard and they became somebody else. That was sort of a challenge, but we did it." (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 1)

By DS9 Season 4, Michael Westmore believed a potential mistake that could foreseeably happen was for one of the makeup artists under his supervision to paint a Klingon blue. ()

The emphasis on the Klingons in "The Way of the Warrior" (along with a heightened focus on the Jem'Hadar in , the fourth installment of DS9 Season 4) had an effect on the design of the Breen in , the fifth episode of the show's fourth season. ()

"The Sword of Kahless" 
A relationship between Worf and Kor was begun and complicated in subsequent DS9 Season 4 installment , a show built on asking the audience whether they would want the Klingons to acquire the title weapon, which was essentially a Klingon version of the Holy Grail. "We just wanted to do a big, fun, dumb Klingon show," said Robert Hewitt Wolfe, smiling, "with a twist, because this is Deep Space Nine [....] And the answer is no, you wouldn't want them to [obtain the revered artifact], because they're psychos." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 110) In fact, the writing staffers were eager to make the pair of Klingons become particularly irritable and haughty, to bizarrely manic degrees. "We wanted to explore the notion that there were some dark streaks to be revealed within these characters," explained scripter Hans Beimler. () As for how effective depicting the Klingons in this way turned out, Beimler stated, "The wonderful thing about these two guys, Worf and Kor, is that while they represent the new and the old Klingon – although Worf is very different from your average Klingon – they both desire the Sword of Kahless and [...] neither one of them [ultimately] feels worthy enough to keep it. That was an interesting arc." () Wolfe mused, "I don't think Worf and Kor were unattractive in this show as much as they were alien to everyone; they have their own kind of ethics and culture, and there are things they would kill for that we don't quite understand. Or we do understand and that's what scares us. Like the Ferengi, they can sometimes embody some of our negative qualities." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 110) Indeed, the writers wanted to make the Klingons in the story responsible for their own behavior, rather than blaming it on a virus or some other power. "If there was any tech that infected them and created this, then they had an excuse for their behavior and we didn't want to give them an excuse," recalled Beimler. "We wanted it to come out of their own ambitions and their own characters." The Klingons ultimately disposing of the Sword of Kahless was also planned. "We knew we wanted them to throw it away," noted René Echevarria. (Cinefantastique, Vol. 28, No. 4/5, p. 40)

The Klingon makeup used in "The Sword of Kahless" was more simplified and less severe for John Colicos than it had been in "Blood Oath", taking half the duration to be applied. "I spoke to dear old Michael Westmore about three times on the phone, so on 'Kahless', they used a water base around my chin and that gave me no problems whatever," Colicos recollected. "Plus, they cut the time down too, by painting the forehead and the nose before I sat in the chair. I was only in the chair for two hours on 'Kahless', as opposed to four hours on 'Blood Oath'. I tried to get rid of my wig but they wouldn't go for it. I guess you have to be Christopher Plummer before they'll let you be a bald Klingon." ()

While filming "The Sword of Kahless", John Colicos and Michael Dorn hardly ever saw each other out of makeup. When Colicos first saw Dorn without the Klingon prosthetics, in fact, it was about the sixth day of the production schedule and Colicos didn't recognize Dorn at all. (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) The topic of their conversing certainly wasn't Klingons. "We talked about acting and everything else in the world, but not about Klingons," said Colicos. "When you're doing it 16 hours a day, you really don't want to stick your finger in the wound." () Colicos very much liked the arguing between the two characters. (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) He was also pleased with how the story involving them had mythic proportions, saying, "[That] is the kind of direction I like to go in with these characters [of the Klingons in general]. They should be larger than life." (Cinefantastique, Vol. 28, No. 4/5, pp. 59-60)

Ira Steven Behr and René Echevarria thoroughly commended the Klingon portrayals delivered, in "The Sword of Kahless", by Michael Dorn and John Colicos as Worf and Kor respectively. (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8; Cinefantastique, Vol. 28, No. 4/5, p. 40) "The scenes were kind of different – the way they got into arguments and the nature of the conflict between the two men," Echevarria observed. (Cinefantastique, Vol. 28, No. 4/5, p. 39) Director LeVar Burton noted that he thought the episode contained "good Klingon stuff." (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) Following his work on "The Sword of Kahless", Colicos was uncertain if the Klingons would keep being prominently featured or not. (Cinefantastique, Vol. 28, No. 4/5, p. 60)

The Klingon characters of Gowron and Kor never met on screen, although Kor speaks about Gowron in "The Sword of Kahless" and they are again mentioned in conjunction with each other in . At one point during the fourth season of DS9, Robert O'Reilly suggested, "It would be fun to have Kor and Gowron get together in a show." ()

Further DS9 Season 4 
In , the crew of a Klingon Bird-of-Prey was scripted as fighting against a boarding party of four intruders from the Cardassian freighter Groumall – namely Dukat, Damar, Tora Ziyal, and Kira Nerys – and being completely overpowered by them in hand-to-hand combat. With the Bird-of-Prey having a crew complement of sixty Klingons, exactly how to film so many Klingon bodies littering the deck was a concern for Director Jonathan West (as well as the obvious difficulty of convincing the audience into believing the scale of the Klingons' defeat against only four opponents). Ultimately, Assistant Director B.C. Cameron suggested to West that the Klingons might instead be beamed back to the freighter. As Ira Steven Behr and Hans Beimler were reluctant to entirely write out the hand-to-hand warfare, they opted to have a few of the Klingons involved in the altercation when the invaders first arrived, then all the Klingons to be beamed to the Groumall. ()

With the Klingons rapidly establishing themselves as an integral aspect of Star Trek: Deep Space Nine, Ron Moore once again found himself exploring new facets of their culture. The first Klingon-related episode he wrote for DS9's fourth season was , in which he once more focused on the brotherly relations between Worf and Kurn, such as the impact on Kurn of Worf having opposed Gowron in "The Way of the Warrior" and Worf's Klingon family, the House of Mogh, having been consequently dishonored by the Klingon Empire. () Moore felt that, by the episode showing Worf as initially being prepared to ceremonially kill his brother, it "says a lot about the Klingons and Worf and honor and how they view their place in the universe." ("Moore Klingon Mastery", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 13) He was starting to feel slightly anxious, though, about the Klingons being portrayed as such a ritualistic society with a tendency to commit suicide. "By this point ritual was de rigueur. It was hard to do Klingon shows without some ritual aspect, because there was a certain expectation that that's what they do. You had to go there, but you were always thinking, 'Have we done too much of this?' We had to draw these lines very carefully, because they sound like they're crazy – they just kill themselves at the drop of a hat." ()

The interactions between the Klingons in "Sons of Mogh" elicited a mixed response from Tony Todd. "I liked the fact that the relationship between Worf and Kurn was still unresolved," he stated. "The Klingons needed Worf to come back to their planet and to be who he was and it was up to Kurn, to a large extent, to bring that about." () Todd uncomfortably thought, however, that an uncharacteristically Klingon outcome ended the episode, with Worf wiping Kurn's memory – which the actor believed was an overly "easy" result – and Kurn thereby being written out of the Star Trek franchise. "I felt it was really a disservice to people that were really [...] into the Klingon legacy," Todd criticized. "It seems like they were eliminating all the best Klingons and creating more cartoon versions [....] I don't think Klingons do anything easy. Not that Klingons need to discuss much, but I think there should have been some sort of massive fight about it." ("A Question of Honour", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 13)

Although "Sons of Mogh" doesn't feature his character of Gowron, Robert O'Reilly witnessed the Klingon portrayals in that episode. He noticed the Klingons seemed to be in deep trouble with the Federation. "But that's just part of being a Klingon, being in trouble with someone," he remarked. ()

Ever since the episode  was originally pitched, the story ended with the twist that the Klingons had faked an incident to make it seem as if Worf had mistakenly shot down a ship full of people. ()

A "Klingon threat" was suggested by Ronald D. Moore for Mark Gehred-O'Connell, who devised the story of , to include in that episode. The Klingon subplot was intended to establish that the Klingons were now in cahoots with the Maquis. However, this idea was dropped from the episode. ()

The DS9 writers had always believed the Klingon crisis was secretly motivated by the Founders, even if that was just because the Klingons were being made paranoid by the Founders. However, the creative group also always wanted to reveal the Klingons might be being more overtly controlled by the nefarious Changelings. This notion affected how the Klingons are portrayed in season four finale , of which Robert Hewitt Wolfe noticed, "We play a bit of the rising Klingon tensions before the [next] episode begins." (Cinefantastique, Vol. 28, No. 4/5, p. 70) The Klingon plotline was important to the writers. René Echevarria remembered, "We were in the process of realizing how we could change the situation with the Klingons, and essentially bring an end to the Klingon war. We wanted to close the chapter on it and get back to what the franchise had been." Offered Ira Behr, "Season 4 threw us for a loop, with the whole Klingon thing [....] I didn't want to have the Klingons as our enemies." () Nonetheless, the writing staff knew they would be presenting "a big situation with the Klingons again," in Ron Moore's words, at the start of the next season, even though the difficulties with the Klingons was only one aspect of the vast challenge Captain Benjamin Sisko had to deal with on the series. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 102)

DS9 Season 5 
By DS9 Season 5, Robert O'Reilly thought the relationship between his character of Gowron and Worf had become a connection which had been long-lasting. "We play off each other very well," he stated, regarding his on-screen interactions with Michael Dorn. ()

By the same time in the making of Star Trek, Michael Westmore's makeup department had many forehead molds ready for portraying Klingons. "We've got somewhere between thirty-five and forty different heads," explained Westmore. "We haven't had to sculpt new molds for years – we're able to adapt what we have, matching and changing them around, maybe making a little plate to glue over a section that will make it seem totally different." ()

The Klingons were further dealt with in DS9 fifth season opener . "Now that [...] we'd made a commitment that the Klingons were part of Deep Space Nine, we had to find out what their role was and try to use them effectively. 'Apocalypse Rising' was our first major attempt to do that," remembered Ron Moore. Even though he was apparently Star Treks "Klingon guy", the Klingons in "Apocalypse Rising" were handled by Ira Behr and writing partner Robert Wolfe, as they wrote the episode together. Moore didn't mind, as he was meanwhile about to begin work on a DS9 Klingon episode of his own writing, . "I may have the reputation of being the Klingon guy, but other people have good takes on them, too," he stated. Additionally, Moore was happy that more than one writer was involved in developing the Klingons, so they could introduce new aspects to the species. ()

Ira Behr once remarked that, by having "Apocalypse Rising" show a Founder had replaced a high-ranking Klingon and been secretly manipulating the species, the show's creative staff established, "It wasn't the Klingons [turning against us]." () However, the identity of the replaced Klingon changed from Gowron to Martok while the show was being written, as did the nature of the episode, changing from a two-parter to a single installment. If "Apocalypse Rising" had been a duology, the first part would have ended with Sisko, O'Brien and Odo being made to look like they were Klingons, which takes place midway through the final version of the show, though a much greater deal would have been made of these aesthetic alterations in a two-parter. Science Consultant André Bormanis imagined the three characters were somewhat altered at a cellular level to fool a standard Klingon sensor sweep. ()

Changing Sisko, Odo and O'Brien to look Klingon irritated some of the actors playing those characters. "It was one of those things that you just have to get past, because it's just different points of view," said Ira Behr. "We, being the ridiculous writers that we are, thought the actors would be amused by it. But they were extremely unhappy." O'Brien actor Colm Meaney related, "I remember that Michael Dorn was very much looking forward to the fact that we would get to experience what he has to go through every day and he would get to gloat." Like Dorn, Odo actor Rene Auberjonois took pleasure in seeing how the Klingon makeup caused discomfort for Meaney and Sisko actor Avery Brooks. "It was gratifying to see them so miserable," he noted. Auberjonois, used to wearing Changeling makeup in his role as Odo, also enjoyed wearing the Klingon prosthetics and found it comparatively very easy to do so. "The only mildly uncomfortable aspect about it was the teeth, which I could pull out between takes," he reflected. Because Auberjonois was enthusiastic about the Klingon makeup during production, the task of applying the makeup to Brooks and Meaney was made slightly easier. "Our principals who are not usually Klingons had suddenly become Klingons," Steve Oster emphasized, "and some of them had issues with putting on heavy makeup [....] With all of his gushing, suddenly no one could say anything negative about it, because Rene was saying how great it was compared to what he normally goes through." Behr noted, "They wound up doing fine." () Robert Wolfe remarked, "I enjoyed seeing our characters in Klingon makeup, our regulars. They pulled it off really nicely." (Cinefantastique, Vol. 29, Nos. 6/7, p. 26)

Preparing and filming all of the episode's Klingon extras wasn't any easier than with the regular performers. () Robert Wolfe commented, "Klingon makeup is so costly, and we had so many people in Klingon makeup, we spent a lot of money." (Cinefantastique, Vol. 29, Nos. 6/7, p. 26) Makeup Artist Camille Calvet elaborated, "We had so many Klingons we couldn't get everybody in the makeup trailer. Only the principals got time in the trailer. I believe there were upwards of forty a day who came through. And they were there all week. People came in waves." Steve Oster added, "Each of those Klingon extras had a makeup and hair person work on them. And we had to bring in extra wardrobe people for all the Klingon accoutrements. We had an army of support people on that episode, people who came in at three in the morning to start applying makeup." Since Michael Westmore's makeup department had fortunately been fitting Klingon prosthetics for years, the situation wasn't as choatic as it could have been. "The extras all got standard foreheads that were made out of the many molds we have on hand for Klingons [....] But they did have their own teeth cast up," Westmore specified. "Each one had his own individual set of brand-new custom-molded teeth that I made out of acrylic." ()

Visual effects were used to give the impression of even more Klingons in "Apocalypse Rising" than the quantity of extras actually there. By doing some split-screen work, the creative team attempted "to make the forty to sixty Klingons look like one hundred fifty and two hundred," as expressed by Jonathan West. He continued, "On some of the wider shots, we divided the group into three and sometimes four segments, locked off the camera, and shot pieces of the group. Then [...] each of the four pieces were seamlessly integrated [by the visual effects artists] into one shot, making it look like there were four times as many people." ()

Although the script of "Apocalypse Rising" describes the Klingons as sitting in chairs, the DS9 producers later rethought how the Klingons were to be positioned. "[They] said that Klingons wouldn't sit around," explained Set Decorator Laura Richarz. The episode's Klingons were eventually portrayed as standing around a series of statues, which were deliberately designed to resemble Klingon characters mentioned in the past. ()

In "Looking for par'Mach in All the Wrong Places", the might of the Klingons was again pitted against Quark's wiles. A couple of the episode's Klingon personas (namely Grilka, who returned from "The House of Quark", and Worf) were originally based on characters from the play Cyrano de Bergerac. () In "Looking for par'Mach in All the Wrong Places", the Klingons were portrayed differently than usual, as the episode is essentially a domestic comedy. "It was time to look to other aspects of them, to play other colors, to do something a little different," recalled episode writer Ron Moore. "I wanted to keep finding other elements of the society that we hadn't displayed as much, and the domestic side was something that we hadn't played." The depiction of Klingons in "Looking for par'Mach in All the Wrong Places" took its cue from "The House of Quark", Moore having realized the species could be shown in a comedic way. () However, Phil Morris, who appeared as Thopok in "Looking for par'Mach in All the Wrong Places", stated, "Klingons are formally Type-A personalities. That's how it was explained to me when I auditioned. They're macho. They talk about how bad they are." ()

Thirty Klingons were originally to have been featured in DS9 installment , depicted on a planet where the Klingons were at war. Because the creation of so many Klingons would have entailed spending the installment's entire budget on makeup, the writers had to rewrite the whole episode three days before it entered production, taking it off the Klingon planet. ( audio commentary, TNG Season 7 Blu-ray special features) A dying soldier encountered by Jake Sisko in "Nor the Battle to the Strong" was originally conceived and written, by teleplay writer René Echevarria, as a male Klingon who had been blinded in battle. In the same early permutation of the script, he and Jake grew to admire each other, over the course of days. "I kept telling him [Echevarria] that we couldn't do it because the whole show was predicated on the idea that the Klingons, the enemy out there, were what's frightening Jake," Ira Behr recollected. "And once you humanize them and empathize with them, the fear level comes down too much." The Klingon was eventually replaced with injured but seeing Starfleet officer Burke and, in retrospect, Echevarria agreed that making the Klingons consistently barbaric was the right thing to do. "The end of the story has to do with this relentless, unstoppable enemy coming in, and we would have just spent eight pages with one of them who we liked a little too much," he reasoned. ()

DS9:  made the change in the Klingons' facial appearance part of Star Trek canon. Ron Moore recollected, "Early in the discussions [about that episode], we knew, 'Well, there's these Klingons that don't look like our Klingons. Got to address it; hard to put Worf in a room with them and say they're Klingons and not comment on it, boys and girls!" ("Trials and Tribble-ations: Uniting Two Legends", DS9 Season 5 DVD/TOS Season 2 Blu-ray special features) Since the episode was a 30th anniversary special, it seemed the perfect opportunity to finally establish a canon explanation for the makeup change, but the DS9 writing staff believed all proposed in-universe explanations were preposterous and ridiculous. (; "Trials and Tribble-ations: Uniting Two Legends", DS9 Season 5 DVD/TOS Season 2 Blu-ray special features) Even the likes of dyed-in-the-wool TOS fans such as Ron Moore and fellow DS9 writer-producer Rene Echevarria as well as Ira Steven Behr couldn't manage to get a workable, simple explanation for the makeup change into the episode. () Hence, the writing staff tried to deal with the issue in as minimal a way as possible. "There's no way around this," conceded Moore, "so we just said, 'Just have Worf say it's a long story and leave it at that, you know? And that's fine.' And it's a wink and a nod to the audience, like, 'Okay, we know this doesn't make sense. Just go with us, okay?" ("Trials and Tribble-ations: Uniting Two Legends", DS9 Season 5 DVD/TOS Season 2 Blu-ray special features) The comment, which was thought up by Ira Steven Behr, thereby discreetly makes light of the fact that the producers and writers of Star Trek had debated for years whether or not to lay this question to rest, once and for all, by incorporating the subject into an episode. Behr explained about the line, “It came out of the story break. It got a huge laugh in the room. We knew we had to deal with the question, but it's really an annoying, boring question, because the real answer is obviously that makeup has changed over the years, in terms of money and quality. We wanted to shine it on, but not really shine it, and having the line 'We do not talk of it,' come out of Michael Dorn’s mouth seemed to work.” (The Magic of Tribbles: The Making of Trials and Tribble-ations) However, Dorn himself wasn't entirely happy with the line. "That's an easy way out," he criticized. "Maybe we should have really dealt with it. Then again, that's another show in itself." (Cinefantastique, Vol. 32, Nos. 4/5, p. 93-94) Due to leaving the question of why the Klingon appearances had changed so much essentially unanswered, Moore, while working on DS9, later announced, "We have no explanation for the smooth-head/bumpy-head transition and nothing in the show should be taken as addressing that point."  For recreating some old-style Klingons in "Trials and Tribble-ations", the Klingon-playing actors had to be made up with the same swarthy, shiny brown makeup as used in the original series. (The Magic of Tribbles: The Making of Trials and Tribble-ations)

During the making of "Trials and Tribble-ations", the name "Klingon" was difficult for returning guest star Charlie Brill to pronounce, which Ira Steven Behr challenged him to do. "He tried to get me to say Klingon without the G," stated Brill, "but I'm from Brooklyn, so it's always going to be Klin-gone instead of Kling-on." 

The DS9 writing staff felt that establishing the Klingons as a threat on the series took a lot of time and distracted the writers from what they ultimately wanted to concentrate on, which was the Dominion. "We only recovered our equilibrium," commented Ira Behr, "in the middle of fifth season, following another meeting with the studio in which we said, 'How about making the Klingons our friends again? You'll see them as much as you want, but we want to get back to the Dominion." ()

When Martok is left on-board Deep Space 9 at the end of fifth season offering , the writing staff intended to unite him and Worf as friends. "Their agenda is not one of scheming or plotting or politicking. It's warrior to warrior," J.G. Hertzler observed of the characters. ()

Much to Ron Moore's delight, Ira Steven Behr gave him the challenge of writing, for Star Trek: Deep Space Nines fifth season, an episode which they pretended to be from a series all about Klingons, an installment ultimately entitled . At first, Moore immediately began plotting a story about Worf and Martok taking a Bird-of-Prey to a Klingon outpost which the Empire had lost contact with, the pair then finding that all the Klingons were missing from the outpost. The duo then paid a boatman to row them across a fog-enshrouded lake nearby; on the other side, Worf and Martok hoped to be reunited with Worf's father, Mogh, and a friend of Martok's. Stated Moore, "I was trying to show the inner life of the crew of a bird-of-prey and do this big out-there kind of piece [....] Ira said, 'Let's just go with Star Trek: Klingon and tell a story.' So we cut all that loose and it became a show about Martok and Worf [and Dax] on the bird-of-prey, going out on a mission." ()

It was of paramount importance to Ron Moore that each member of the Klingon crew be portrayed as having their own personality. "What was important to me was giving that ship an inner life, in the sense that you walk in and each of the people there would have his own specific character and backstory and relationships." Moore struck upon the notion that this was "a beaten crew, one that had gone through some tough times and seen some horrible things." Placing the Klingons in this situation facilitated his interest in concentrating on their individual characteristics. () He explained, "I [...] wanted the crew of the Rotaran to stand apart from other Klingon ships, to get the sense that these guys had really been through some rough times and that it was becoming apparent to anyone who encountered them."  Moore actually thought it important to give each of the crew members not only their own personality but also a distinctive look, conscious of an issue with earlier episodes involving multiple Klingons. "On some of the shows where we've had a lot of Klingons on camera, even I get them confused," he confessed. "So we wanted more visual distinction here." () He referred to his interest in allowing the audience to tell the Klingon officers apart as his "primary concern."  To emphasize their distinctive personalities, Moore wrote a speech for Dax about there being "strong Klingons and weak Klingons." He later explained, "I wanted to say that Klingons are people too." Even though Moore tried to accentuate the differences between the Klingon crew members, he had them unite in song, thinking this was "just the kind of thing that Klingons do" because they are, in his opinion, similar to Vikings. ()

Casting the Klingon roles in "Soldiers of the Empire" turned out to be a difficult process. () However, at least one of the cast members, Kornan actor Rick Worthy, was overjoyed to appear as a Klingon, because they were one of his favorite types of character, in this DS9 episode highlighting the species.  With hindsight, he related, "Playing a Klingon was so much freakin' fun...the hair, the face, the Klingon teeth, the way they speak and walk and their wardrobe..I always saw the Klingons as a combination of Japanese Samurai who haven't had their morning coffee (or tea!) and African Zulu warriors." 

Ira Steven Behr ended up disappointed with the Klingons in "Soldiers of the Empire". He complained, "[In addition to the difficult casting process], I don't think the makeup always helped the actors. None of it went far enough [....] These were supposed to be the baddest guys [....] And people in the bar [at Quark's] talk about them like they're bad guys, but they're not badass at all. Throughout the entire show, without a doubt, the toughest man on the ship is Martok. And that totally screwed up the show in my mind." ()

A Klingon B-story, concerning Nog endeavoring to gain their respect, was included in  for a couple of reasons. As well as the plot thread adding to the characterization of Nog, Ira Behr felt the most significant motive for doing the B-story involved the Klingons themselves, as he wanted to demonstrate that Martok was still alive after "Soldiers of the Empire". "It kept the Klingon presence alive, which I thought was important to do at this point," Behr explained. ()

By the end of DS9's fifth season, the Klingon makeup included approximately thirty-five different ridged forehead designs, representing the various Klingon Houses. Applying the Klingon features took longer than they had required during the making of the original series. "People would be surprised to know the make-up only takes 20 minutes," commented Michael Dorn. "It's the gluing of the hair that takes most of the time. When we can speed that up, I'll be a happy man." On the other hand, the task of wearing the makeup had become progressively easier, including for Dorn as Worf. "The forehead weighs less than an ounce," said Michael Westmore, "but he's only glued around the edges now, which could also mean more touch-ups." (Star Trek 30 Years, p. 57)

DS9 Season 6 
At about the start of DS9 Season 6, Ronald D. Moore wasn't losing confidence in his ability to write about Klingons. In fact, he declared that the one thing he did "best" was to "sit around and talk about Klingons all day." 

To have the Klingons participate in the Dominion War depicted in DS9, the writers had to minutely change the Klingons' typical gung-ho attitude. Ronald D. Moore clarified, "The Klingons can't be too suicidal. They're fighting a long and bitter war against a very strong opponent. They do have to husband their strength and their manpower to a certain extent." 

Somewhat ironically, the war-fanatical Klingons were featured, amid a Dominion War arc consisting of six episodes, in DS9 Season 6 outing , though that installment focuses on family relationships rather than war. () Depicting the Klingon perspective of the Dominion War resulted in writing partners David Weddle and Bradley Thompson being assigned to pen the installment. "To take the Klingon side of the war and really personalize it in a different way, interested them," said Ira Behr. However, writing for the Klingons in "Sons and Daughters" was difficult for Weddle and Thompson, who wrote the episode as their first assignment after joining the DS9 writing staff. "We found that you don't need to be nearly as stiff as we thought," remembered Weddle. "We made the dialogue more formal than it needed to be, because we were so concerned about writing Klingon dialogue correctly, rather than relaxing and giving the characters more humanity." Two scenes the writing partners were particularly proud of both involved Klingons. The first was one in which Worf and an adult Alexander Rozhenko practice using a bat'leth for defense, and the other was a scene wherein a group of Klingons mock Alexander in the Rotarrans mess hall. Even though both Worf and Alexander were obviously Klingon in general, the alien nature of both characters wasn't always essential. For instance, Weddle noted about the former scene, "[It] resonated as a father and son relationship that transcends Klingon lines." (Cinefantastique, Vol. 30, No. 9/10, pp. 38 & 37) That relationship, as portrayed in "Sons and Daughters", was even influenced by a terrestrial source of inspiration, as the installment's depictions of Worf and Alexander were based on the characters of Lieutenant Colonel Kirby Yorke and son Trooper Jeff Yorke from the Western film  respectively. The writers were intrigued by the prospect of filling in some gaps in the relationship between Worf and Alexander. "And we enjoyed playing against expectations [in basically putting an end to their connection] [....] The relationship between [Alexander] [...] and Worf was more or less resolved by the end of 'Sons and Daughters'," stated Bradley Thompson. ()

Speculation about Klingon ages was involved in the writing of "Sons and Daughters". "We [...] said, 'We really have no idea how quickly Klingons grow up," Bradley Thompson relayed. The conclusion the writers reached, after many long discussions regarding this subject, was that "Klingons are not humans, and our Human failings and limitations need not always be pressed on other aliens," as later phrased by Ira Behr. The fact that Klingon-playing performers had to go through three hours of makeup application in the morning was one of several factors which resulted in Alexander Rozhenko, who is reintroduced in "Sons and Daughters", being brought back specifically as an adult and not at a younger age. ()

To play Alexander as an adult, Marc Worden, who guest-starred as the character in "Sons and Daughters" and later sixth season outing , wore the same prosthetic headpiece James Sloyan had worn in the episode "Firstborn". () Worden remarked, "When you're fully suited up as a Klingon, it makes it quite easy to relax. So much work has already been done for you before you step on to the set of Star Trek that it's your job to portray the character as honestly as you can." About the latter of the two episodes he made appearances in, Worden exclaimed, "I found it hilarious in between takes to see two Klingon extras playing backgammon! It was hysterical." ()

Ira Steven Behr was pleased with the Klingon portrayals of Marc Worden and J.G. Hertzler. "Between [them] [...] I think it's obvious that there's still life in those Klingons afterall," he remarked. 

While writing "You Are Cordially Invited", Ron Moore discovered the episode could explore a somewhat puzzling aspect of Klingon society. "I realized that by bringing Jadzia into the House of Martok, I could address the question, 'What's the role of women in Klingon society?" Moore explained. "We'd seen them as warriors, but we had no idea if they would have some other role within the structure of the great houses." () He also said, "One of the things that was important to me was to portray Klingon women differently, to show how they fit into Klingon society." (Cinefantastique, Vol. 30, No. 9/10, p. 44) Indeed, Moore found he could try to correct a particular impression of Klingon society he had instigated years previously, especially on TNG, as he had inadvertently reduced the role of Klingon women. "Looking back on it I didn't think that was a good decision [....] The fallout from [establishing, firstly in 'Redemption', that women couldn't sit on the High Council] [...] was that the role of Klingon women got much smaller, and I hadn't intended to do that. It was a real disservice. So I figured that if men run the Council and rule the Houses, maybe women rule the social structure, and within that structure the mistress of a great House wields pretty much unchallenged power." () Moore initially planned to develop this idea more than he did. "We never got around to it, but I was going to say that the mistress of a great house is the one who decides when they have kids, and what the genders were going to be, and how many they were going to have." () Nonetheless, Moore was able to establish, "There is a role for the mistress of a great House. Not all women have to be warriors to be valued." (Cinefantastique, Vol. 30, No. 9/10, p. 44) These notions of equality and the value of Klingon women went on to influence the portrayal of the relationship between Martok and his wife, Sirella, as well as a full-blown Klingon wedding. (; )

The most major event in "You Are Cordially Invited" is a Klingon wedding, marrying Dax and Worf. Ron Moore wanted to "give a Klingon spin" to the wedding. (Cinefantastique, Vol. 30, No. 9/10, p. 44) He thereby returned to the theme of Klingon domesticity he had written about in "Looking for par'Mach in All the Wrong Places" and was given another opportunity to deepen Klingon culture. () "These are people who eat heart of targ," Laura Richarz remarked about the Klingons. "We'd never seen this particular side of them before." () Moore wanted the Klingons, via the marriage, to be shown as a mature species who valued one another, took their responsibilities seriously, and held sacred other elements than merely Kahless. "I didn't want them to literally all be worshipping Kahless, although they do on some level," he continued. "I think Klingons have a polytheistic kind of society." () Moore expected "Klingon fanclubs some place" would start imitating the Klingon wedding ceremony. (Cinefantastique, Vol. 30, No. 9/10, p. 44)

DS9 Season 7 and later Voyager 
The Klingons in fourth season Voyager installment  were particularly miserable. Though Neelix actor Ethan Phillips was uncomfortable with wearing both his usual Talaxian makeup as well as Klingon prosthetics, he enjoyed performing Neelix's stint in Klingon ephemera. "Klingons are outrageous to play, especially those guys we played," Phillips observed. "They were just nasty people [....] We [sang] some drunken songs and stuff like that. You know, it was fun." (VOY Season 4 DVD easter egg) For the same episode, Foundation Imaging used a CGI Klingon to portray a member of the species falling off a ledge, one of multiple instances wherein CGI figures were used to represent Klingons. ()

In , it was rumored that the next Star Trek series after Voyager would probably be about the Klingons, set on their homeworld. Ron Moore dismissed this as "just a rumor." 

Much of Michael Westmore's workload during DS9's seventh and final season consisted of Klingon foreheads for the character of Worf (along with Vorta ears for Weyoun). () By the time John Colicos reappeared as Kor in season seven installment , the Klingon prosthetics were definitely not so impractical as they had been in "Blood Oath". "The make-up took far less time to apply," analyzed Colicos, "and getting it off no longer rotted my skin." ()

In "Once More Unto the Breach", the Klingons were again written by Ronald D. Moore. "I saw it as probably the last big Klingon show I was going to do," he reflected. (Cinefantastique, Vol. 32, Nos. 4/5, p. 48)

The DS9 writing staff thought it would be interesting to feature a conflict between Martok and Kor in "Once More Unto the Breach". The idea of the rivalry was thought up early in the episode's development. While the staff writers were either breaking the story or scripting the episode, they chose to have the feud be the result of a Klingon class system. (Cinefantastique, Vol. 32, Nos. 4/5, p. 48) Ronald D. Moore realized the Klingons employed this facet of society after considering the significance of Klingon Houses. "In 'Once More Unto the Breach'," Moore explained, "that [class system] gave me a chance to say something else – birthrights and royal blood did matter to these guys [....] It's inevitable if you're going to have a society that's founded on houses [most of which presumably were deemed not good enough to sit on the High Council] [....] That naturally stratifies the society. There've got to be guys [...] who had to work their way up and claw for every ounce, and there were guys [...] who were of noble blood. And the actors had always played it that way." () Indeed, Moore believed the invention of the Klingon class system "made sense," owing to how John Colicos and J.G. Hertzler played their respective Klingon roles of Kor and Martok. (Cinefantastique, Vol. 32, Nos. 4/5, p. 48) "I stumbled onto the idea of making it a class thing between them," offered Moore. "That just felt right with their personalities [....] There was a natural antipathy between the two characters." () He also stated, "It seemed like a natural chasm between the two." (Cinefantastique, Vol. 32, Nos. 4/5, p. 49) Though establishing the once smooth-browed Kor as possessing "superior bloodlines" seemed to contradict The Final Reflection referring to Klingons with smooth foreheads having lower status in the Klingon Empire, Moore explained, "I didn't set out to deliberately refute anything in 'The Final Reflection.' To be honest, although the book did influence some of my early thoughts on the Klingons, I haven't read it in at least fifteen years or so and I don't really remember all the nuances of Ford's take on the Klingons."  The stratification of Klingon society mentioned in "Once More Unto the Breach" underwent revision later in the show's seventh season. ()

In "Once More Unto the Breach", the Klingons were also used to explore the issue of old age. "That was another part of Klingon society we hadn't seen – the elderly," Moore reckoned. "It's not cool to be an old Klingon. It's not pretty when you get past your prime and you're out of power in the Klingon Empire." ()

Ronald D. Moore liked how Martok and Kor are represented in "Once More Unto the Breach", commenting, "It is definitely the story of Martok and Kor [....] The scenes are so great with [them]." Moore especially approved of one of their scenes in particular, in which Martok mockingly antagonizes Kor while he says nothing for a long time. "I think it is a difficult scene to watch because you like both characters," Moore observed. (Cinefantastique, Vol. 32, Nos. 4/5, p. 49) Additionally, he stated, "It spoke volumes about the characters and their society." ()

Though Kor dies in "Once More Unto the Breach", Ron Moore suspected there were some Klingons who continued to hold a grudge against him. "When the entire Galaxy is at war and they need everyone they can," Moore hypothesized, "they won't go to Kor because he has too many enemies [....] The Klingons let things run really deep, and the guys that Kor screwed over on the way up probably still didn't forgive him." ()

Although no Klingons appear in VOY Season 5, Naomi Wildman actress Scarlett Pomers witnessed several Klingon-playing actors while she was preparing to appear in the fifth season Voyager episode . "When I walked into the makeup room, [...] there were Klingons getting made up," she recalled. ()

Originally, a Klingon-Romulan hybrid man named Joss, who harbored a hatred towards Klingons, was to have been an antagonist in the film  (when it had the working title Star Trek: Stardust). In a story treatment written by Michael Piller and dated , the Klingons and Joss' opinion of them were referred to in a statement which said, "Joss hates Klingons as much as Worf hates Romulans." This was mentioned while Joss was attending a captain's dinner aboard the Enterprise, at which he made an insulting remark about the Klingons who had been slaughtered at Khitomer, a comment that deliberately offended Worf, as his Klingon parents had died as a result of the massacre. He and Joss subsequently engaged in two bat'leth fights, firstly combat which Picard insisted had to be merely a first-blood contest and was held on the holodeck, as well as a later fight-to-the-death in which Worf finally managed to slay Joss. In a subsequent treatment (dated ), Joss' Klingon heritage was removed from the story (making him fully Romulan) though multiple references to Klingon practices were included, such as "a Klingon martial arts foot maneuver" Worf had taught Deanna Troi and used by her against Joss. In the same treatment, Worf and Joss still fought in a battle to the death in which Worf, just before killing Joss, called "for strength from the Klingon gods" and, thereafter, bellowed "a Klingon victory cry." (Fade In: From Idea to Final Draft) Although the final version of Star Trek: Insurrection includes no appearances by any full- or half-Klingon characters apart from Worf, the film does delve into the effects of Klingon puberty.

After working on Star Trek: Insurrection, Michael Dorn stated about Klingon makeup in Star Trek films generally, "It's the same makeup [as on TV], but the movie makeup is a little more intricate. They really get in there and make sure that it's smooth in areas so it doesn't show or whatever because your face is 75 feet wide across the screen, and any type of little boo-boos you're going to see." (Cinefantastique, Vol. 32, Nos. 4/5, p. 94)

During the creation of , the difficulty of portraying Klingon anatomy resulted in Worf and Ezri Dax, after a romantic night together, being depicted waking with all their clothes on. "It was this whole production question. What does a Klingon look like under his clothes?" Ira Behr remembered. "It was just too complicated to think about." ()

Although Ron Moore had suspected "Once More Unto the Breach" would be his final "big Klingon show" while he was writing it, he wasn't entirely finished with the Klingons. For instance, René Echevarria, while writing , set up a Klingon political scenario (involving Gowron and Martok) for Moore to pay off in the next installment, . Of that outing, Echevarria noted, "Ron got to do the final Klingon episode." (Cinefantastique, Vol. 32, Nos. 4/5, pp. 49 & 73) The Klingons underwent cataclysmic changes in "Tacking Into the Wind". Even from the time Moore wrote his first draft of the installment, the episode was to feature a conflict between Worf and Gowron, due to the quantity of Klingons who Gowron was sending to their deaths as the Dominion War raged. (Cinefantastique, Vol. 32, Nos. 4/5, p. 74) The writers consistently planned for Martok rather than Worf to become the permanent Klingon Chancellor, in "Tacking Into the Wind". "I didn't think that the Klingons would accept Worf as their leader after all that's happened," explained Moore. () In his second draft of the outing, Moore decided to include some social commentary on what the Klingons had become. The idea he could do so, having Ezri Dax make some remarks about how the species had become corrupt, didn't occur to him until he was writing the second draft. "That's when I realized that this was my last opportunity to do anything with the Klingons, these aliens that I had been involved with for a long time. I wanted to view the Klingons in a different manner, and look at what I'd created with the same cold eye as Ezri. Yeah, these guys are corrupt, and Worf has put up with that for a long time. They talk a good game about how honorable they are, but they're not capable of living up to their ideals. I thought, 'That's an important thing to say, so let's say it." () Ultimately, Moore was happy with how both Gowron and Martok are depicted in the episode. (Cinefantastique, Vol. 32, Nos. 4/5, p. 76) The high death rate of Klingon leaders meant that Robert O'Reilly wasn't surprised by his character of Gowron being killed off in "Tacking Into the Wind". "I had always gone into Star Trek knowing that the life of a Klingon leader was not very long," O'Reilly reasoned. () During production on "Tacking Into the Wind", a volatile debate between Worf and Gowron as well as a subsequent, choreographed fight between them took an entire day to shoot. ()

By the end of Star Trek: Deep Space Nines run, Robert O'Reilly came to the conclusion that both Worf and Martok had been corrupted by having too much contact with Humans. (Star Trek: The Official Starships Collection, issue 47, p. 13) Conversely, J.G. Herztler felt strongly that the Klingon way is evident in Martok drinking over the death of millions of Cardassians in DS9 series ender and seventh season finale  while the character does not understand why Sisko and Admiral Ross don't join him in doing so. "I think it was true to the Klingon culture to do it that way," Hertzler stated. ()

At the conclusion of DS9's series run, Michael Dorn mentioned that applying the Klingon makeup took about two-and-a-half hours. (Cinefantastique, Vol. 32, Nos. 4/5, p. 94)

Ron Moore was left unsatisfied, at the end of DS9, that the opportunity to do his Klingon Hell story idea hadn't presented itself.  He resurrected it for Star Trek: Voyager, in which it became the season 6 episode .

Having always been interested in exploring the Klingon side of B'Elanna Torres, a showcase which allowed Roxann Dawson to do exactly that was provided to her in the form of "Barge of the Dead", not only delving into the Klingon Hell, Gre'thor, but also the history between Torres and her deceased mother, Miral. (Cult Times, issue #56, p. 39) Regarding how Klingons are portrayed in the installment, Dawson said, "It was [...] a chance to bring the Klingon world to the forefront in such a classical way, which you really couldn't do otherwise in a show like Voyager." ()

"Who's Killing the Great Voyagers of the Delta Quadrant?" – a story which "Barge of the Dead" co-writer Bryan Fuller proposed for Voyagers sixth season – included multiple versions of Voyager, one of which was a Klingon equivalent of the ship. This version was from an alternate universe in which the Klingon Empire had conquered the Federation, two hundred years in the past. 

Though he played multiple Star Trek roles (such as Humans, an Iyaaran and an Eska), Eric Pierpoint found the Klingon makeup for his part as Kortar in "Barge of the Dead" took the longest to apply. () Similarly, Roxann Dawson believed that, by the seventh and final season of Voyager, the make-up required for her role of B'Elanna Torres had deteriorated. During that season, she complained, "I despise putting on the B'Elanna make-up [....] I think that after seven years, the make-up is the only thing that has just gotten worse and worse and worse, and it is almost unbearable." Although Dawson's half-Klingon make-up seems less complex than a full layout of Borg prosthetics for one drone, the former actually took more time to apply. ()

 Enterprise 
By setting  primarily about 100 years before , ENT creators Rick Berman and Brannon Braga made available for themselves an opportunity to reinvent the Klingons. The pair wanted to again make the species fierce and antagonistic, eliminating the sense of understanding and détente which had been established on Star Trek: The Next Generation. (Star Trek: The Official Starships Collection, issue 41, p. 10) They also sought to make the early Klingons of ENT more primitive and rustic than the Klingons of later centuries, such as proposing (in the pilot episode ) that they routinely "sharpen their teeth." ("Broken Bow" audio commentary, ENT Season 1 DVD & ENT Season 1 Blu-ray) The series bible for Enterprise declared, "Klingons [...] will be far more primitive than those Picard and Janeway will know. They have not yet given up the practice of sharpening their teeth or eating the hearts of their enemies." Braga stated at the time, "The Klingons are much more gnarly and frightening than they were in Kirk's day, where they talk and are quite polite. In Archer's day, they shoot first and ask questions later." (Star Trek: The Official Starships Collection, issue 41, p. 10)

Despite Enterprise being set largely prior to Star Trek: The Original Series, the ENT creative team didn't want the species to return to how they had looked in TOS. "We also weren't going backwards into the modified forehead with very little facial hair, which was the movie version," explained Michael Westmore, "so they decided to stay with the look I created in 1987." Because Costume Designer Robert Blackman decided to have lower necklines for the earlier Klingons, Westmore designed them to have "a clavicle appliance that glues on the front, so they have this distinct bony clavicle." Westmore proceeded to state, "We weren't trying to do the Klingons too differently. The character has been acceptable for 15 years, so we didn't want to go back several hundred years to a pre-Klingon and say they've evolved that fast." () Supporting the decision to continue using the bumpy-headed Klingon makeup, Dan Curry said, "We're just doing the best work we possibly can and letting it speak for itself." () On the other hand, Rick Berman admitted, "It's all a little bit sketchy anyway." ()

Some consideration was given, at about the start of Enterprise, as to whether the producers would try to explain the reasoning for there being two different-looking types of Klingon. Shortly before the series began, an uncertain Rick Berman revealed, "We've thought about it [....] I think it is something we have discussed possibly doing." () Brannon Braga agreed, "We'll see. We may begin to explore that dichotomy."  Mike Sussman commented, "The staff has talked about showing their evolution into the 'smooth-headed' and more cutthroat Klingons of the 'TOS' era. I don't know about the smooth foreheads, but I'd be interested in finding out why the Klingons never talked about honor in all the years Kirk dealt with them." ()

An initial concept which Executive Producer Brannon Braga thought up for the series pilot of Enterprise, , had Klingons attacking Iowa en masse. This was later changed to a single Klingon crash-landing in Broken Bow, sparking off the Broken Bow Incident. ()

The Klingons of  were based on the crew of the Russian submarine Kursk. However, the prospect of writing for the Klingons was not the aspect of the episode which most appealed to "Sleeping Dogs" teleplay writer Fred Dekker, as he instead was much more attracted to the premise and setting of the story and always preferred Enterprise stories that introduced new alien races. Although he believed "Sleeping Dogs" could have worked just as well with such a species, Dekker accepted that it made perfect sense for the Klingons, they having always been Star Treks equivalent of the Russians, to represent the Kursks crew. Also, considering how little experience Captain Archer and his crew had of Klingons, Dekker was somewhat able to treat them like a new species. Aside from a general notion that the Klingons should appear brutal and alien, he was provided with much creative freedom in depicting the species. "For me," said Dekker, "the point was to acknowledge the Klingons as 'people' – to find them in a clear position of distress [....] The idea to 'humanize' their plight was mine, and it wasn't anything I thought about as far as canon. It just seemed right." (Star Trek: The Official Starships Collection, issue 41, pp. 10-12) By that time, the altered Klingon makeup schemes were so well known that a scene description in the final draft script of "Sleeping Dogs", introducing the Klingons physically into the plot, proclaimed, "We immediately recognize familiar ridged foreheads." The same script pointed out that both Klaang (in "Broken Bow") and Bu'kaH (in "Sleeping Dogs") were, at one point for each Klingon, unwillingly strapped to a biobed in the sickbay of . Also, in dialogue that was written into that script but omitted from the episode, Captain Archer commented to Bu'kaH, regarding her species, "From what I know about Klingons, you enjoy a stiff drink now and then."

In a story conceived and pitched by Taylor Elmore for the first season of Enterprise, the Klingons put Archer on trial. The story was not produced at that time, though. ( audio commentary/podcast)

Hoshi Sato actress Linda Park approved of how the Klingons were shown during the first season of Enterprise. Shortly after production on that season wrapped, Park raved, "Although they're not really our enemy, there seems to be a great comedic thing happening between the Klingons and us that I think is a really cool thing. It brings some levity to the situation, and shows a new side to the relationship between the Klingons and humans that hasn't necessarily been looked at before in the Star Trek legacy. At least I don't think it has." () Rick Berman likewise enthused, "I think our more primitive Klingons have been fun." ()

Conscious that there were many ways to depict the Klingons on Enterprise, Mike Sussman felt that the writing staff of the show's first season were "a little guilty" of taking "the least interesting choice" of how to portray them. He described this as showing them "behaving in exactly the same way as they will in the 24th century." () At the end of the first season, Brannon Braga similarly critiqued, "We did one Klingon show too many. So far, we seem to be helping them all the time. If we're going to do Klingons again, we need to make sure they're bad guys and start hinting at how they became our enemies. They haven't exactly been the titanic villains you might expect yet." ()

 ENT Season 2 

Since writing staffers had the opinion they were not reaping the full benefit of the Klingon species in the writing of Enterprise, a concerted effort to show the Klingons in a more villainous light was made in the show's second season. This began with the episode , of which Brannon Braga said, "We definitely wanted them to be bad guys. It was ultimately not as satisfying as it could have been, though." ()

As a sign of the times,  deemed the reappearance of Klingons in a film production any time soon wasn't foreseeable. The magazine hypothesized, "It's more than likely that the Klingons have had their motion picture day, for the moment at least."

Around the time when  was released, Michael Dorn made some comments in which he conceded that, if the film was successful, he would very much like to see an entire series about the Klingons. Dorn was even willing to partake in the making of such a series, if Rick Berman called him with plans for it to be a companion series to Enterprise. This was despite hating the makeup for the role of Worf and doubting a Klingon-centric series was going to happen. (, Star Trek Nemesis supplement, p. 14)

Klingons were scripted to be referenced in . However, they are not mentioned in the final edit of that episode.

Amid the second season of Enterprise, Larry Nemecek suggested the series' writing staff might address the issue of Klingons having bumpy foreheads in the era of the show's setting, though such an episode was not (yet) announced. () Even though he admitted that the DS9 writing staff hadn't managed to "make sense of" the change amongst Klingons in "Trials and Tribble-ations" and that the bumpy foreheads of the Klingons on Enterprise seemingly contradicted previously established canon, Nemecek remained faithful that an explanation would be included in the future of Enterprise, encapsulated in "a good story." ()

The ENT Season 2 installment  picked up the "Marauders" plot thread of worsening relations between the Klingons and Starfleet. "It was an opportunity to delve into what Klingons were like during this period in history," said Brannon Braga. () The Klingons in "Judgment" were played by many performers. For some shots apparently taken inside a vast Klingon courtroom, some of the actors were digitally duplicated, so as to make the crowds of Klingons seem even bigger than the quantity of performers portraying them in those scenes. ( audio commentary/podcast) For scenes from "Judgment" which are set on Rura Penthe, about fifteen or twenty actors were cast as Klingon guards. First Assistant Director David Trotti recalled, "We managed to find some big, burly biker-looking guys to be our Klingons, much like back on the old Star Trek VI [Rura Penthe] set." ("Enterprise Secrets", ENT Season 2 Blu-ray special features) Compared to "Marauders", "Judgment" had a more successful representation of the species, with Braga calling it "an interesting insight into Klingon culture." () Rick Berman cited the installment as "a great example of the intensity the Klingons can bring to Star Trek." ()

The prospect of writing about Klingons was what immediately appealed to David A. Goodman about writing "Judgment". He wrote a Klingon-centric story that was married with the plot idea Taylor Elmore had pitched, a year earlier. ("Judgment" audio commentary/podcast) Goodman included multiple Klingon references in the episode and tried to use it to explain the differences between how TOS had established the Klingons and how they are depicted in TNG. "I shoved as many TNG Klingon references as I could into there, and most of them stayed in so I was very happy about that [....] It was fun for me to write this episode that was an attempt to explain [....] And I was sort of saying that the Klingons themselves were undergoing a kind of crisis as a culture that would lead to the Original Series Klingons but that the basis for the Next Generation Klingons would be under the surface." 

The penultimate installment of the second season, , was to feature the Klingons more than they are in the episode's final version, some of their involvement in the story having been substituted by the Tellarites. Brannon Braga recalled how the writing staff thought about the Klingons at the outset of writing the episode: "Why do Klingons again?" () Even in the final draft script of "Bounty", the Klingons were written about in ways that did not match how the species is represented in the final version of that episode. At one point, Archer stated, "If I know anything about the Klingons, other than they smell terrible, it's that they won't make the same mistake twice." Klingon captain Goroth later implied that Klingon honor demanded that, if a prisoner offered a bribe to his or her captor, the captor would have to cut off the prisoner's hands. It was also stated with certainty in the script that the Klingons were going to double the reward on Archer's head, though this possibility is instead changed to being only "likely" in the final version of the episode.

By the time of Enterprises second season, the Klingon mythos had been built up over the years to such a point that Duras actor Daniel Riordan once remarked, "The whole Klingon legacy is so rich." Riordan was fascinated by the Klingons. A helpful aspect in shaping his performances as Duras was noticing that Klingons in general seem to be a mix of high intelligence with animal-like aspects. Of the latter quality, Riordan said, "Everything's real basic in terms of their bodies, their physical lives. Their emotions are excessive in violent terms." ()

To portray Klingons in the second season finale , Klingon-playing actors had to submit themselves for the application of their make-up, which started at five in the morning. Later that day, the performers were sought by assistant directors who ensured they were on set on time. As part of an exclusive tour of the sets for an article in , Penny Juday visited the Klingon set while battle footage involving members of the species was being filmed there. "Watching the whole scenario unfold," she reported, "makes you realise just how little these particular bad guys have changed over the years [....] Clustered in a small group [in a set-aside recreation area for actors not immediately needed] are some Klingons in full garb, eating ice cream bars, drinking Coke and slurping coffee, all the while making small talk about things like how the kids are doing in school. It's a very surreal sight, as well as somewhat comedic [....] Scott Bakula is swapping mock insults with the Klingons. 'These darn Klingons and their manes – it's all about their hair, and how costly tending the Klingon's hair can be, holding up the crew... again!' he chides with a wide smile on his face." ()

Brannon Braga was ultimately disappointed with how the Klingons are portrayed in "The Expanse". He stated, "There was a part of me that thought the Klingon scenes were [drab and] shoehorned in there." A friend of his disagreed with him about this issue. ()

During Penny Juday's set visit involving some Klingon-playing performers, it was rumored on the set that the Klingons would appear in the third season, for more confrontations with Enterprise. () However, this did not come to pass.

ENT Season 4 
The season 4 Enterprise episodes  and  finally explained the Klingon makeup differences, as Manny Coto and his team of writing staffers decided they did want to address the issue before Enterprise concluded its run. "It was an opportunity," stated Coto, regarding the option of telling a story that bridged the two variations of Klingon. (Cinefantastique, Vol. 37, No. 2, pp. 40-41) However, the writers never had very much interest in offering a canonical explanation for why the Klingons lost their forehead ridges, so they didn't set out to write such a story, though they had heard multiple ideas over the years. The notion of explaining the Klingon transformations came about from an idea Mike Sussman had about the Human Augments. He specifically pictured the Klingons finding an Augments ship, from , which had not been completely destroyed. (Star Trek: The Official Starships Collection, issue 53, pp. 14 & 15) After Sussman consulted Coto about this idea, they together imagined the Klingons firstly suspecting the Humans were trying to create genetically engineered soldiers and secondly using Human embryos in efforts to create enhanced Klingon soldiers. The pair of writers then realized this allowed them to meanwhile reveal how the Klingons ended up looking more Human-like by the time of TOS. The prospect of demonstrating this also helped explain the alteration in the Klingons' temperament and disposition. (Star Trek: The Official Starships Collection, issue 53, p. 16) "Obviously, all the Klingons we saw in The Original Series would have been human-fusion Klingons who had survived, or been descended from people with the augment virus," Sussman remarked. (Star Trek: The Official Starships Collection, issue 53, p. 17)

In the final draft script of "Affliction", the altered Klingons were initially referred to as "fierce-looking aliens" and were further described thus; "The aliens have a swarthy complexion, and dark facial hair... they could easily be mistaken for Humans. We'll eventually learn these are Klinqons... but their cranial ridges have disappeared." Later in the same script, a bracketed note in the stage directions commented, "[The] augmented Klingons should have a slightly altered temperament. Although they still have a hard edge, they may also be smug, sarcastic and a little arrogant... they're less concerned with honor than other Klingons. In many ways, they're more Human than the warriors we're familiar with."

Ultimately, Mike Sussman thought, in retrospect, that the two-parter of "Affliction" and "Divergence" possibly helped account for why TOS Klingons "possessed many horrible qualities" and were seemingly "without honor." However, he additionally said, "Maybe we could have highlighted that a bit more – that the Klingons were honorable, but had changed because of the Human DNA in the virus." (Star Trek: The Official Starships Collection, issue 53, p. 17)

Phlox actor John Billingsley appreciated the effort to do a Klingon two-parter that explained their evolution. As well as admitting he believed it was an "interesting" idea, he said, "I thought there was something puckish about Manny Coto's willingness to actually attempt to give a reasonable answer to that question." () In another interview, Billingsley stated, "I thought it was lovely that Manny, who obviously was such a fan of the original show, was prepared to have a two-episode, you know, arc devoted to, 'Why do the Klingons look different?' I mean, I thought that was kinda lovely." ("Before Her Time: Decommissioning Enterprise, Part Two: Memorable Voyages", ENT Season 4 Blu-ray special features) John Schuck, who played Dr. Antaak in the Klingon-centered two-parter, similarly "loved that story about how the Klingons got their ridges." 

In hindsight, Brannon Braga was uncertain how successful Star Trek: Enterprise was in its endeavor to make the Klingons more primitive than before. "To be honest [...] I wonder if they look any different," Braga commented, with a laugh. "How do you make a Klingon more Klingon-y? I think it was great in concept. I'm not sure if the Klingons ever were more gnarly." ("Broken Bow" audio commentary, ENT Season 1 DVD & ENT Season 1 Blu-ray)

The Klingons were to have been conquered by the Romulans in the unproduced animated series Star Trek: Final Frontier, set during the 2460s.

In the unmade series Star Trek: Federation (pitched by Bryan Singer), Klingons would have sought enlightenment as well as a good fight. (The A-Z of Star Trek, Special SFX Edition, pp. 106 & 107)

Klingons of the alternate reality 

While devising the plot of the  film , screenwriters Alex Kurtzman and Roberto Orci dismissed the notion of featuring the Klingons as the primary villains of the film, which Orci and Kurtzman set in an alternate reality they invented especially for the movie. The filmmakers decided not to use the Klingons as the main antagonists because they felt that to do otherwise would have seemed like regressing the portrayal of the species, since the Klingons had been accepted as heroic figures in TNG. (Geek Monthly, issue #7, p. 043)

A new look for the Klingons – featuring masked helmets with ridges on the forehead – was created for a Klingon-centric deleted scene from Star Trek. Director J.J. Abrams was at first unsure how he wanted the Klingons in the film to look. Costume Designer Michael Kaplan recounted, "J.J. said, 'I don't really have an idea exactly what they should look like, but I do want them to be really, really, really scary." The idea of not creating full-facial Klingon makeups for the film, using helmets instead, was thought up by Abrams. ("Klingon Wardrobe" featurette, ) Although the movie's script described the masks worn by the Klingons of the alternate reality, the script also referred to the members of the species as "scary," with "hideous faces" barely visible underneath their helmets. 

Once the helmets were designed, the Klingons' facial features were considered. Joel Harlow, who created the makeup designs for the Vulcans and Romulans in the film, stated, "The Klingons were a race that really wasn't addressed makeup-wise until, you know, maybe a couple weeks before we shot it." ("Klingons" featurette, ) At his suggestion, the makeup artists who collaborated on the movie did some preliminary work on designing the faces of Klingons from the alternate reality. "It was never really a given when we got started, but Joel said, 'I think we should sculpt a Klingon and have the pieces ready just in case,' so that's what happened," said Richie Alonzo, who worked closely with Harlow on the film. ()

The makeup included a small part of the brow to be seen through the helmet, as some of the Klingons were to be shown in close-up. ("Klingons" featurette, ) "Because wardrobe already had a helmet for the Klingons, we had to fit our makeup design under it, and make them work together," said Richie Alonzo. "You never really see what they look like, so we didn't want to come up with a specific look that we would be stuck with." () Joel Harlow noted, "We knew that there had to be something there other than a paint job." Harlow, who sculpted the brow segment himself, felt it was fortunate that only a small portion of the brow had to be visually updated. The only other element of the makeup were faux beards. ("Klingons" featurette, )

Into Darkness 
Before it was even confirmed that his production company Bad Robot would be involved in a sequel to the Star Trek film, J.J. Abrams was highly interested in including Klingons in such a movie. (deleted scene "Prison Interrogation and Breakout" audio commentary,  & Three disc Blu-ray)) Once his connection to the film was announced, Abrams conceded that "it would be hard not to" introduce them in the alternate reality. (SFX, issue #200, p. 60) Because the Star Trek movies Abrams directed were always about reinventing and modernizing familiar aspects without losing their essence, it was virtually inevitable that Klingons would feature into the sequel film, entitled . However, the Klingons were temporarily written out of the film, when it was at a stage of early development. (Star Trek: The Official Starships Collection, D4 Bird-of-Prey Special Issue, pp. 6 & 9) Abrams commented, "I do think that the idea of doing Star Trek and bringing Klingons into the world is an obvious and cool challenge. And how do you do it?" Producer Bryan Burk felt likewise, commenting, "Klingons are ingrained in the tapestry of Star Trek as any other villain, so you desperately want to get them in sooner than later." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features) Roberto Orci also felt the pressure to incorporate the species in the sequel. "Some fans really want to see Klingons, and it's hard not to listen to that," he admitted. "The trick is not to do something that's been seen before just because you think it will be a short cut to likeability." (SFX, issue #200, p. 61)

Joel Harlow predicted that the Klingons would indeed be featured in the sequel to the film Star Trek, saying, "That's gonna be a great challenge because the Klingons, I think, more than any other alien race beside the Vulcans, are known worldwide. So, how do you update that?" ("Klingons" featurette, ) Makeup Designer Barney Burman wanted to give the Klingons a new facial design for the sequel. "I would like to do the same kind of treatment on them that was done with the Romulans," he said, "and bring them into the new millennium." (SFX, issue #200, p. 60) In hindsight, Richie Alonzo remarked, "We thought it would be great to redesign the Klingons, and make them really cool-looking for the next film." ()

Lead Creature Designer Neville Page was also eager for the Klingons to return. In , he named them as "the one" species he would most like to tackle in the sequel. He proceeded to explain, "My approach would be to try and come up with something that's a unique look but is still a Klingon obviously. Because I think if I did them really tall like say 9' and instead of brown made them blue, I might get into a little trouble! But I would try think about them as real deal people -- and I know other designers have -- but really give them a history and a motivation. Understand why they're dressed the way they are. Understand their rationale for long hair and facial hair. Make sense of those physical features which they typically have, which are the ridged foreheads." Page added that, not being entirely sure how he would tackle the species, he had started contemplating ways to distinguish Klingon races; "There are different physiological ticks even in the Klingon world. Maybe they are all brown, but the ridges are the African ones, the fewer ridges are the Asian ones. I don't know." 

Klingons were written into the story for the twelfth Star Trek feature film, . However, early in the genesis of that plot, a few iterations of the story involved a fleet of Klingons heading to Earth in pursuit of retribution, at the climax of the tale. The Klingons responded to  diplomatically intervening by returning back the way they had come.  Despite this undeveloped climax being dropped, the Klingons still remained in the film's narrative.

Because the alternate-reality Klingons had only ever been depicted with their helmets on at all times, the creative staff of Star Trek Into Darkness had to work out how they looked without the helmets on. "We definitely wanted to do [that]," J.J. Abrams noted. ("The Klingon Home World", , ,  & Star Trek: The Compendium special features) Since only one scene had depicted the alternate reality variant of Klingons and it had been deleted, the makers of the new film were given free reign to reinvent their look. This opportunity was made the responsibility of Neville Page, Michael Kaplan and makeup department head David LeRoy Anderson. Richie Alonzo concluded that, for many of the makeup artists who had worked on the previous movie, the chance to redesign the Klingons "never materialized." () On the other hand, Abrams remarked, "We were very lucky to have Neville Page and David Anderson work on bringing the Klingons to life." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features) Stated Page, "With this one, it was that perfect case of, 'We have to top ourselves,' or at least take the helmets off. And, because of that, there were all sorts of opportunities to do in this film what I'd thought of for the first one. So I had a good three, three and a half years to let my ideas for the Klingons gestate." 

The Klingon makeup scheme in Star Trek Into Darkness had to be highly detailed, so it could withstand the scrutiny of IMAX. "So, the makeup had to be great and the application had to be great," remembered J.J. Abrams. ("The Klingon Home World", , ,  & Star Trek: The Compendium special features)

The aforementioned sense of creative freedom drove Neville Page's designs. David LeRoy Anderson reported, "Based on the versions that I saw Neville produce, I think he was not committed to anything, and free to explore a new direction." Heather Langenkamp, Anderson's partner at makeup shop AFX Studios, added, "Neville generated lots of amazing ideas about their appearance." () According to Anderson, Page and J.J. Abrams "got pretty far out there" with their Klingon facial concept designs before "it started to come back." Anderson elaborated, "Everyone was trying to pay homage to the fans' idea of the real race while wanting to innovate something new...." (, Issue 287, p. 87) Indeed, Page and Anderson agreed with this notion. ("The Klingon Home World", , ,  & Star Trek: The Compendium special features; ; ) "It's a real balancing act," Anderson professed. "You don't want to stray too far, but you also don't want to go back and cookie-cut the exact same thing. There have been a lot of advances and we have the opportunity to do a new, fresh pass without losing anything."  In agreement, Page himself specified, "As much as we wanna bring something fresh to the table, we also want to make sure that it is respectful to the culture. I studied [the] Klingon [language] quite a bit, and spoke to a lot of [Klingon fans] [....] There was this one treatment, a piercing element that the Klingons have, and few would recognise it, but those who are serious fans will catch it." 

The actors playing Klingons in Star Trek Into Darkness were cast if they looked intimidating. Props Master Andrew Siegel remembered, "We thought, 'Okay, these guys should be badass.' We cast all real imposing guys and they are scary.”  The notion of making the Klingons brutal-looking reflected on elements of their culture. "That was something I gravitated towards," acknowledged Siegel. "The main thing for me was: 'What are these characters like?' They are incredibly barbaric. I wanted all of their props to reflect that." () The brutality of the Klingons was definitely central to the design of their world. Production Designer Scott Chambliss recollected, "One of the early notions that I had was that they might be at war with themselves as well, much the way that we are, on our planet." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features) Despite the attempts to aesthetically highlight their barbarism, an effort was made to make the Klingons look somewhat appealing. Neville Page said, "One thing I tried to do with the Klingons, which was a tough one, is make them sexy: a beautiful-ugly group of men. I think we got it. Not that the previous actors were ugly, but it was a very conscious choice of who we cast, a very conscious sculpting of the Klingon form to make them look sexy. In a way."

The preparatory time of about three and a half years helped Neville Page formulate how he would like the new Klingons to look. "Then, when it came time to show J.J. my ideas," he said, "I had thought about it all so much that I was just ready to go on the Klingons."  At a point when production was well under way, the first Klingon facial sculptures were digitally created, which Page did using . () A gallery of his Klingon concept designs can be found here.

Not entirely happy with the original sculptures, David Anderson tweaked the designs. "David put little changes on them," said Heather Langenkamp. Because ongoing production on the film meant that Anderson was extremely busy, however, he hired makeup artist Earl Ellis to tweak the designs. "Neville's artwork was beautiful," commented Anderson, "but it was translating into a very heavy makeup that would have concealed all of the features on the performer if we used that sculpture." () Anderson also clarified, "When we studied the 3D rendering, we realized the proportions would have resulted in areas of makeup that were three or four inches thick. That would have limited the actor's ability to perform." (Cinefex, No. 134, p. 85) Ellis concurred, "The designs were tending to look a bit more mask-like, and we really needed a makeup approach." () The group specifically realized that, by using massive blocks of foam rubber on the faces of the performers, they would end up making all the actors look exactly the same, whereas the creative team intended for each individual member of the species to be different-looking. 

Earl Ellis thereafter contributed to the design process. Continued David Anderson, "I said, 'I'm afraid the flavor and essence of the Klingons is not coming across here,' so Earl looked at the illustrations, and immediately understood what they represented, what we could use, and what to leave behind. He was able to translate Neville's ZBrush creation into an actual functioning makeup that allowed the actors' performances to come through." () In essence, the makeup team's solution to their predicament was to leave the Klingon faces more exposed and use multiple prosthetic pieces, allowing for more expressive facial movements.  Ellis himself recalled, "When Dave showed me the designs, I recognized a lot of design elements that had been put into these characters. If you look at any of the episodes from the past 20 years, they have a certain color scheme that says, 'Klingon,' and you can't go too far from that. So I recognized those elements, but the design was sleeker, and more elegant. Not just some bestial character [....] The less you put on somebody, and the thinner the pieces, the better they can act, so that's the approach we took [....] It's tough to do the Klingons, because they kept changing over the years." ()

The design ultimately chosen for the Klingons of the alternate reality had the top of the head accentuated. "It's really what defines the Klingons, kind of their forehead and their hair," observed Neville Page. "So, in looking at the forehead, I thought it would be interesting if that forehead ridge shape continues all the way around the back of the head. The piercings, the idea behind that is kind of like marking the side of your World War II bomber with victories. They mark their bodies with victories, either with piercings or scarification." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features)

As the Klingon helmets had impressed J.J. Abrams to a great degree and since they had already been paid for, the helmets actually appear on-screen in Star Trek Into Darkness. () Earl Ellis foresaw some potential difficulty with trying to combine the Klingon head prosthetics with the helmets. "That would have limited the size of the heads," he speculated, "but because I took a makeup approach, that was fine." ()

Once the makeup for the alternate-reality Klingons was designed, extra modeling techniques were employed. "We then will print out three-dimensional models as reference models that I will give to the makeup department," explained Neville Page. "And the makeup department will then interpret those on top of our selected actors." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features)

On at least one day, Sean Blakemore's Klingon makeup was applied by Makeup Effects Artist Jamie Kelman, who reported, "This makeup is a long one. This one actually takes about four-and-a-half hours." The final detail in the application process was the addition of jewellery. After having a metallic earring secured to his left earlobe, Blakemore jested, "Now I am officially blinged out." Wearing the makeup got hot for the actor underneath it. ("The Klingon Home World", , ,  & Star Trek: The Compendium special features)

The filmmakers were highly satisfied with the new Klingon makeup design for Star Trek Into Darkness. "Once Earl finished his sculpture of the Klingon character on our two actors, we brought them to set for a show and tell, and J.J. Abrams loved them," David Anderson reminisced. "There was no critiquing; it was just, 'Yes, we've got our Klingons!' He could see that they were two completely different beings, but from the same planet, and they were really nice, subtle and thin makeups." () Referring to the redesigned Klingons, Abrams described the collaboration of Anderson and Page as having resulted in "a great design and the great makeup." He went on to say, "I think [it] is a pretty cool, intimidating look and [...] I think David really did an amazing job." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features) Earl Ellis not only described the new Klingons as looking "more elegant" than they had in the past but also reckoned, "I think the fans will be very happy with them." Heather Langenkamp commented, "Of all the make-up we did, we're most proud of the Klingons. It's really powerful and fantastic. There's something very regal about it." () Langenkamp was personally happy with the makeup herself, saying, "I think, technically, the Klingons are the most beautiful makeups in the movie. It looked so great on the actors." 

On the first day of shooting the Klingon scenes in Star Trek Into Darkness, the relevant actors were lined up and introduced to J.J. Abrams by First Assistant Director and Co-Producer Tommy Gormley prior to final preparations being made to the Klingon costumes before filming. To a camera documenting the occasion,  actress Zoe Saldana commentated, "It's like Sports Illustrated for Klingons. They look so handsome." Indirectly referencing 's relationship with Uhura, she joked, "I don't know. If I was Spock, I'd be nervous." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features)

Again, some footage of Klingons in the alternate reality was deleted. The edited material from Star Trek Into Darkness included a scene in which, following a battle between the Klingons and an away team from the Enterprise, two Klingons had  on the ground and brutalized him while standing above the captain. The pair of Klingons, including the officer played by Sean Blakemore, accepted the surrender of the other Starfleet officers in the away team – Spock, Uhura and a security guard – but struggled with them, shooting the guard, and were about to kill Kirk when  intervened, killing the Klingons themselves. 

Nowadays, there is once again no explanation for the introduction of redesigned Klingons. Earl Ellis concluded, "You just have to accept them for what they are. There's no real reason why they should look the way they do now, compared to the original series, but they still have all the elements that say 'Klingon'." () By way of explanation, J.J. Abrams mused, "You know, it sort of honors what has come before. But in the many different series, they were all very different. We followed suit." ("The Klingon Home World", , ,  & Star Trek: The Compendium special features)

When quizzed about plans for a third Star Trek film produced by Bad Robot, Damon Lindelof was noncomittal about whether Klingons would return but admitted, “You can never see enough Klingons, and I think in this film [Star Trek Into Darkness] we've given the audience a little taste, but there's also a promise that there's a larger conflict on the horizon, and that would be fun to see."  Although Bad Robot released  as its third Star Trek movie, in , no Klingons are featured in that film.

Discovery 

Page returned to redesign the Klingons on the CBS All Access series .  Collaborating with creature and makeup effects designer Glenn Hetrick at Alchemy Studios and initial showrunner Bryan Fuller, it was decided to make the Klingons bald with a long line of python-like sensory pits running from the forehead down the back of the head, which, together with the ridges, would imply that each of the species' heads was one large sensory organ. "That was born out of Bryan saying he wanted them to be able to see, quite literally, behind themselves," Page said. 

Hetrick stated the in-universe rationale for the show's hairless Klingons was a story where Kahless cut off a lock of his hair, put it in lava, and twisted it to forge the first bat'leth – the Klingons have therefore shaven off their hair as a symbol of unity. However, this was not mentioned on the show. He explained, "We're obsessed with that story. And as we unpack it, we're going to find tons of other reasons for the Klingon look." 

Page sculpted the new Klingon skull design digitally, to determine the basic shape of their heads. 

 was the initial costume designer on Discovery: Gersha Phillips, who replaced her after Fuller bowed out of the show, explained Larlarb tried to make the Klingons feel less human by giving their costumes a broad breastbone, to emphasize the notion they have twice as many as organs. "I think the main thing is to create a species that doesn't have so many human components, as opposed to how they were in other iterations of Star Trek," said Phillips. "Trying to camouflage as much of the human body as possible." 

Phillips also revealed, "I feel like they [the CGI artists] even wanted to do more with eyes and things like that, but were limited by how much screentime they had."

Popular culture and trivia 
The popularity of the Klingons has grown over time. In , Richard Arnold mused, "For good and bad, the Klingons have become really prominent in Star Trek and in Star Trek fandom, in spite of having made only eight appearances on the original series." () Noting the impact that the Klingons had on fans of the original series, D.C. Fontana laughed, "They suddenly became really popular for us!"  According to Majel Barrett, the reason why the TOS Klingons were (much to Gene Roddenberry's distaste) consistently portrayed as evil was because "the fans insisted they be represented in that way." (Cinefantastique, Vol. 22, No. 3, p. 20) Jeanne M. Dillard – in her book Star Trek - Where No One Has Gone Before (paperback ed., pp. 184 & 186) – described Kor, Koloth and Kang as "the original Star Treks favorite Klingons" and "the three best-known Original Series Klingons." At the time, the Klingons were so popular that, after William Campbell played Koloth in "The Trouble with Tribbles", he received fan mail that included people writing about the Klingon eyebrows he had worn. Also, the children in Campbell's neighborhood teasingly referred to his wife as "Mrs. Klingon." (The World of Star Trek, p. 120) When Ruth Berman tried to account for the makeup differences in TOS Klingons, she did so in response to a fan letter which enquired into the reasoning behind the changes in Klingon makeup for "The Trouble with Tribbles". (These Are the Voyages: TOS Season Two) On one occasion during the second season of TOS, a teenage fan misidentified Walter Koenig, upon encountering him at O'Hare Airport in Chicago, as a Klingon. In hindsight, Koenig remembered, "[He] froze in his tracks in front of me and in total befuddlement screamed loud enough to stop hearts, 'OH MY GOD, IT'S WALTER KLINGON!" (These Are the Voyages: TOS Season Two, "Foreword")

The portrayals of Klingons in the original series have been successful with production staffers. Robert O'Reilly has been passionate about the species ever since watching the original series. () As a fan of that show from the second half of its first season onwards, O'Reilly had long-standing aspirations to portray a Klingon. "If you had asked me at any time throughout the years which role I wanted to play on Trek," he admitted, "it would have been a Klingon." When asked why he had this enduring interest in Klingons, O'Reilly responded, "Well, I really like bad guys. I like being able to go a little over-the-top with my acting and have fun with it. I knew I could do a very good job with a Klingon role because I could bring in my Shakespearian background and use my accents in different ways." () O'Reilly is very fond of the Klingon characters of Kor, Koloth, and Kang, with Koloth being his particular favorite. "John Colicos and Michael Ansara were just fabulous [as Klingons], too," he enthused. () David Gerrold also appreciates the Klingons from the original series. He raved, "I just love those Klingons! They're just... they're so self-righteous and arrogant and pompous. You just want to stick pins in them, to watch them explode! But they're the perfect foil for Kirk [....] The Klingons are comic villains of the best sort and, I mean, if you look at the way the Klingons have been played ever since, yes they're villains, but they get some of the best lines, they get the funny lines." As an example of what he meant, Gerrold cited Gorkon saying, "You have not experienced Shakespeare until you have read him in the original Klingon," in . Dave Rossi remarked, "They're no less savage and tricky [than the Klingons in later Star Trek productions] [....] The Klingons in the original series are deliciously clever and backstabbing and ready to kinda stick you with a shiv at any minute." ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray) Star Trek author Keith R.A. DeCandido also developed a fondness for the Klingon culture, ever since seeing  as a boy in the 1970s.  Armin Shimerman summarized, "In the original series, we all loved to hate the Klingons." (Cinefantastique, Vol. 28, No. 4/5, p. 48)

As the underground popularity of Star Trek increased in the years when it was no longer aired after the making and broadcast of the original series, there was a strong portion of fandom that was so passionate about the Klingons that an extensive backstory universe started to grow in the show's absence. () Richard Arnold pointed out, "With Klingons in four of the [first] six films, there was obviously something about them even then." () Although William Campbell characterized the Klingons generally as "the perfect adversaries," he was not pleased with their redesign in The Motion Picture, observing, "When people saw the first movie, they said, 'What the hell is that?' You can't have a guy with a head like a crab become a rival." ( #138, p. 34) Robert Justman was extremely pleased to view how the Klingons are portrayed in The Motion Picture, later commenting, "I was entranced when I first saw the movie and I saw those wonderful bony protuberances. I was thrilled. They were so imposing, frightening, awe-inspiring. It seemed to free the actors so they could shake off their inhibitions and go over the top portraying their characters." () John Schuck disliked the color inconsistency, in Star Trek III, between the Klingon prosthetics and the skin tones of the actors playing Klingons therein. ( #138, p. 30) Todd Bryant remarked about the fans, "They seem really interested in Klingons, that's for sure. There was a big response for Klingons." ( #149, p. 65) Because Leonard Nimoy has always been highly interested in the Klingons (which he termed "our favorite villains") and their culture, Nimoy was regretful that the films he was involved in didn't use all the potentialities of the Klingons that he believes they hold. He commented, "To this day, I wish I could have done a serious study of Klingon culture in one of our films; I think they're marvelous 'dark side' adversaries." (I Am Spock, hardcover ed., pp. 313 & 223)

The response of fans to initial news that the Klingons were to be excluded from The Next Generation was an influence on the alteration of this plan. () The Klingons gained even more fans as aggressive allies of the Federation than they had as its enemies. (Star Trek: The Original Series 365, p. 139) There were early criticisms, though, that Worf was too dissimilar from other Klingons, to which Michael Dorn responded, "If you're expecting a race to remain completely unchanged over time, then you're being rather narrow-minded." () One initially skeptical fan was Ronald D. Moore, who was at first doubtful that the Klingons as allies could be as fun as they had been as foes. He was, however, excited by the Klingon-related possibilities which the addition of Worf suggested. For example, Moore eagerly anticipated seeing "the Klingon version" of such episodes as  or , which had established much about Vulcans and their culture. (Star Trek: The Next Generation 365, p. I1) In , John Schuck similarly voiced concerns over the Klingon makeup and the decision to make them allies of the Federation. "That presumption has yet to pay off in terms of anything I've seen," he complained. "I don't like the makeup for television very much at all. I think it's very arbitrary. They've simplified too much. I think they could do better." ( #138, p. 30) Obviously, William Campbell felt similarly. During the SeaTrek of May , he stated about the revised Klingon makeup scheme, "I had a difficult time with that [....] I never understood the reasoning behind the extensive makeup change except for the reason that it is a new show." In direct response, Majel Barrett tried to explain the change by saying it was intended to delineate them from other TNG species, though Campbell responded by observing that the Klingon attitude had also changed. (Cinefantastique, Vol. 22, No. 3, p. 20) Recalling his own opinion of the Klingons at the time he wrote "The Bonding", Moore stated, "I thought they were a really cool species." ("The Bonding" audio commentary, TNG Season 3 Blu-ray) In 1990, he also professed, "I think Klingons are, by definition, interesting. Their race is a fascinating one." (Cinefantastique, Vol. 21, No. 2, p. 44) Moore especially enjoyed writing Klingon scenes, later reminiscing, "The Klingon guest stars were always fun to write for." (Star Trek: The Next Generation 365, p. 213) Melinda M. Snodgrass echoed Moore's sentiments by saying, "It's an interesting alien culture – it's fun to delve into it and to continue to explore it." (Cinefantastique, Vol. 21, No. 2, pp. 44 & 45) Susan Sackett declared, "Of course, as any fan of the show knows [...] some of the best stories written for the series revolved around Worf, his family, his moral tug-of-war, the Klingon leaders and the decidedly hesitant Klingon faction which seemed temporarily resigned to Federation membership." (Inside Trek: My Secret Life with Star Trek Creator Gene Roddenberry, "Log Entry 37") On the other hand, Michael Piller considered, "If you don't like Klingons and you don't like Lursa and B'Etor fighting for control of the Klingon Empire, then maybe you didn't like the whole Klingon arc we did on Next Generation." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 58) Dave Rossi had a criticism about the TNG Klingons. "It's kind of a shame," he lamented, "that [...] for instance, in Next Generation, Commander Worf [...] just kind of became a measuring stick for how bad the next bad guy was. A bad guy would show up and if he could punch Worf in the face and knock him out, you went, 'Wooh, that guy was bad; he beat up a Klingon!' But in doing so, it kinda defanged the Klingons in a lot of ways. That never happens in the original series." ("Errand of Mercy" Starfleet Access, TOS Season 1 Blu-ray) Nonetheless, Armin Shimerman noted, "A lot of people became quite enamored of the Klingons through Worf." (Cinefantastique, Vol. 28, No. 4/5, p. 48)

Director Cliff Bole – who worked on such Klingon-inclusive episodes as , , ,  and  – valued the considerably overboard nature of the Klingon species and the freedom for inventiveness which they allowed. "I think the Klingon shows are fun to do," he remarked, "because you can go a little broad with them. Who the hell knows what a Klingon is anyway? Who knows how Klingons make love?" (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 182) The book Star Trek - Where No One Has Gone Before (paperback ed., p. 186) makes it clear that, between TOS and the DS9 episode "Blood Oath", the Klingon characters of Kor, Koloth and Kang were "never forgotten by the viewers of Star Trek." The Klingons – including villainous sisters Lursa and B'Etor – were still enormously popular at the time of Star Trek Generations production. This led B'Etor actress Gwynyth Walsh to proclaim, "There's a tremendous curiosity and delight in Klingons among the fans and it spills over to us [meaning herself and Lursa actress Barbara March]." (Star Trek Generations - Official Movie Souvenir Magazine) Despite being impressed with the diverse number of Klingon fan clubs, Walsh felt the appeal of the Klingons logical, remarking, "I can understand completely why Klingons are so popular, and I think it has to do with empowerment. It makes a lot of sense to me that, if you are a female and a Star Trek fan, you would identify with female Klingons." () Regarding the previous movie appearances of the Klingons,  enthused, "They've had a good run, having provided strong aggressive roles." By January 1996, formal reviews of Klingon troops had been held, at many conventions in the United States, with most of the fans wearing full Klingon makeup and uniforms. (Cinefantastique, Vol. 27, No. 4/5, p. 107) In fact, legions of fans dressed as Klingons were highly visible at the conventions, in the years shortly prior to 1996. ()

Somewhat explaining why the Klingons were originally made antagonists in DS9 Season 4, Rick Berman described them as "the villains that people love to hate." () The popularity of the Klingons was meanwhile also evident to Odo actor Rene Auberjonois, who subsequently recalled, "It seemed to me that Klingons were very popular characters." () Shortly before DS9's fourth season, Michael Dorn mused about the Klingons, "Everybody admires their sense of honor. Even though it may have been passé in the years past, it's definitely one of those things that people recognize and respect now. Klingons have a sense of honor, and of going for it, and being up front, and telling it like it is. And I think that's what people like about them." () The US press and fans eagerly anticipated the reintroduction of the Klingons in DS9 Season 4. However, some fans had initial reservations. (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 1) Specifically, there was reportedly some concern from fans that reintroducing the Klingons as villains in DS9 would cause them to resume their militaristic posturing with the Federation, directly breaching one of Gene Roddenberry's personal triumphs in creating TNG. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 101) Remembering another audience reaction, Robert Hewitt Wolfe stated, "A lot of people said they liked [...] the introduction of the Klingons, but that it felt like a departure for the series instead of a natural continuation of the series." (Cinefantastique, Vol. 28, No. 4/5, p. 70) The Klingons remained extremely popular. For instance, midway through the fourth season, Jeanne M. Dillard described the Klingons as having "evolved into Star Treks most popular heroes." (Star Trek - Where No One Has Gone Before, paperback ed., p. 203)

Though depicting Klingons in "Apocalypse Rising" was very expensive, Robert Hewitt Wolfe felt the high costs of portraying the species weren't evident to viewers. "I think people are so used to seeing Klingons that they take them for granted. They don't realize that this is a big deal," he said. (Cinefantastique, Vol. 29, Nos. 6/7, p. 26) Making Sisko, Odo and O'Brien look like Klingons delighted the fans of DS9, though. ()

John Colicos, Michael Ansara and William Campbell guested at a Klingon-themed convention (one of many conventions they appeared at together) which was held in San Francisco, not long before November 1996. "That was a purely Klingon convention, not a Star Trek convention," Colicos reflected. "They were all dressed up. Even the promoters were dressed up. You couldn't tell one soul from another." (Cinefantastique, Vol. 28, No. 4/5, p. 60) Theorizing about the appeal of Klingon cosplay, Marc Okrand, the inventor of Klingonese, offered, "When you're [pretending to be a Klingon], you can do things that you can't do if you're human. You can get away with being demanding and bossy and just saying what you want [...] [which] polite society prevents you from doing. You can step back from that." (Star Trek 30 Years, p. 66) Ira Steven Behr agreed, "It's much easier being a Klingon [than being a human]." () However, Colicos had a criticism about the fans who attended conventions in Klingon garb. "The thing I don't like about some of those people is that they have picked up the brutal aspect and the fierceness of Klingon culture and sometimes, you can almost them with biker gangs. If you're going to go for crudeness and viciousness and cruelty, then I think you're missing the essence of the Klingon character." The actor was, on the other hand, often amazed by the zeal with which the fans pursued their interest in everything Klingon. ()

Walter Koenig believed the statement explaining, in "Trials and Tribble-ations", the Klingons' facial changes didn't work well. "I thought the explanation [...] was a well-conceived idea, but I think it could have been executed better," Koenig reckoned. "It looked like an apology, rather than a gag, and it was really a gag. The most obvious difference from the original series is the way the Klingons look, and it's so obvious that it should be addressed in some way. My sense was that it was designed to be tongue-in-cheek, and it didn't come off as that, as much as just a weak explanation." (Cinefantastique, Vol. 29, Nos. 6/7, p. 81)

By 1997, even people who weren't Star Trek fans knew what a Klingon was, despite the definition of the species and the associated makeup having radically metamorphosed since their first appearance in "Errand of Mercy". After reprising his role as Kor in "The Sword of Kahless", John Colicos reported, "I'm getting fan mail, now that the Internet and Web sites have come alive, from all over the world from people remembering that initial performance and comparing that with the modern Klingons." ("The Sword of Colicos", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 8) In September 1997, Ira Behr observed, "There are [...] fans that like the Klingon shows." 

During the development of the series that became Star Trek: Enterprise, there were rumors that the premise of the forthcoming show would be about the future depicted from the Klingon perspective. (Broken Bow, paperback ed., p. 245) Making the Klingons major recurring adversaries on Enterprise was an attempt to keep all the fans of the species happy. () Even if he was no longer part of the Star Trek franchise, Robert O'Reilly was very happy that the Klingons were a part of Enterprise. He characterized their return as "what I like most" about the series and said he was pleased "as long as Klingons are back." () In a 2002 poll run in  (the results of which were published in the magazine's  edition), readers voted Klingons as their second favorite alien species in Star Trek (after the Borg). () Shortly after appearing as  in , J.G. Hertzler mused about how the simplicity of the Klingons' magnified emotions made them appealing to fans; "The Klingons exist at the outer reaches of emotional behavior. Sadness is magnified, rage, everything. I think the Klingons allow the audience to vicariously participate with these emotionally outrageous and understandable beings and it's a relief. The world is so complex for us now. For the Klingons, things are clear – this is what I hate, this is what I like." ()

By , the Klingons had become the most popular alien species from the entire Star Trek franchise, Vulcans notwithstanding. (Star Trek: The Original Series 365, p. 139) Neville Page disclosed that, upon researching the culture around Klingons prior to crafting their facial redesign for the  film Star Trek Into Darkness, he talked to "the Klingon people at Comic-Con, people who role-play that world."  In May 2013, StarTrek.com ran a poll in which responders selected Klingons as the alien race they hoped to see more of in Star Trek Into Darkness.  Klingons were also cited in a list of "Top 50 Alien Species!" which was published by IDW. Commenting on the selection, comics writer Mike Johnson stated, "Klingons are my favorite species to write for [with Vulcans a close second]. Proud, uncompromising, unrelenting." ("Top 50 Alien Species!", Star Trek: Ongoing issue #50, "Live Evil, Part 1")

Aside from feeling strongly about the Klingons in TOS, Robert O'Reilly – given an intensive insight into how Klingons were played – has been a fan of multiple Klingon depictions. "Every Klingon I've ever enjoyed watching has a tremendous passion, a love of life, a love of honor," he pointed out. "I think you draw some of that from every training you have. It helps to have done a lot of Shakespeare. Shakespeare lends itself to being a Klingon. There's also a lot of pain with the makeup, the hair, the wardrobe. If you can channel that suffering correctly, you can use it." () Despite his long-held fandom of Klingons, O'Reilly once asserted that Trekkies know "more about Klingons than I'll ever know." ()

At the end of his tenure of portraying Worf on DS9, Michael Dorn described Klingons, saying, "I think if you took the aggressive tendencies of Human beings, the naked aggression that we all have in us, I think that would be what Klingons are [....] Klingons want you to be that way. It's like a healthy release." (Cinefantastique, Vol. 32, Nos. 4/5, p. 92) Dorn also talked about how Klingons have been represented as multi-dimensional, suggesting, "You know there's a lot of Klingons that definitely don't have any honor and definitely don't have any morals or any scruples. So, the lesson you have to learn is there are no absolutes [....] You can't just go, 'Okay, I'm a Klingon and I'm going to do this despite everything about you." () Concerning the moral ambiguity, Robert O'Reilly considered, "Maybe that's the key. Maybe that's what 'the Klingon way' is all about; a constant redefining of what it really means to be a true Klingon warrior." () Ron Moore observed, "Some are good, some are bad, some are strong, some aren't. They're not Jem'Hadar." () Keith R.A. DeCandido agreed, "The point is that there isn't a single way to be a Klingon. One of the reasons why Klingons have proven to be so vital as a species to pursue is that there is more to them. And I'd argue they didn't change as much between TOS and TNG as people like to think [....] I'd argue that the Klingons of the 24th century owe plenty to how John Colicos played the role. And the diversity is what makes it interesting [....] That's the point. There is no one way to be a Klingon, although there are basic notions that are constant."  Regarding the consistent aspects, Scott Tipton stated, "Even when Klingons are behaving badly, they typically have been portrayed as charismatic and strangely compelling. Throughout the various incarnations of Star Trek, there has always been a strong implication that the Klingons have a very different view of history than their Federation rivals." () In agreement, O'Reilly philosophised, "The logic of a Klingon is not to [question the leader], and anybody who does that is literally a traitor [....] In war it never matters [who dies]; it's a Klingon thing. People die; it's for the Empire. If you die in battle, that's honorable." (Star Trek: The Official Starships Collection, issue 47, pp. 12 & 13) He elaborated, "On the side of the Klingons, it's like, if you are going to war, you've made that choice, even if you've been forced into it. I don't like war – it's the most horrible thing Man can create. But as soon as you've made that choice, you have to be a Klingon about it and just do it... and do it fully." ()

In a contest to determine favorite Klingons voted by readers of  (a poll which ran between issues 143 and 149 of the magazine, from June 1989 to December of that year), the two most popular characters were Worf and Kor. The poll also distinguished that other frequently mentioned names were Kruge, Kang and Maltz. (Starlog #149, p. 35) The  official reference book , written by Terry J. Erdmann and Paula M. Block, refers to Kor, Kang and Koloth as "everyone's favorite Klingons."

Rick Berman retained a fondness for the Klingons, throughout the years he worked on , Deep Space Nine, Voyager and Enterprise. In the run-up to the initial broadcast of , he remarked, "I'm very partial to the Klingons. They've always been my favourite species. They're a lot of fun and they represent a part of humanity that our 22nd, 23rd and 24th Century humans have sort of shed. I've always enjoyed it when we've had Klingons on our shows." ()

Another production staffer who enjoyed working with Klingons, on both DS9 and Enterprise, is James L. Conway; from the episodes he directed, the ones that included Klingons are , , ,  and . "I love doing scenes with Klingons," he enthused, "I [did] a lot of Klingon scenes over the years, on Star Trek, and I never got tired of it. It was so much fun to do." ("Broken Bow" audio commentary, ENT Season 1 Blu-ray) Regarding the Klingons themselves, Conway analyzed, "I've always thought the Klingons were slightly bigger than life. They're sort of the Genghis Khan/mongrel type of invaders. There's a certain humour to that if you observe their drinking songs and the way they bang their heads. There's something that's charming about these guys!" (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 1)

Another director who helmed multiple Klingon shows was Winrich Kolbe. David Livingston noted, "He always does great with the Klingons." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 72)

Out of all the aliens that Set Decorator James Mees worked with, Mees – who contributed to TNG, VOY and ENT – chose the Klingons as his favorites. "The Klingons have always been the most fun," he commented. "I think that's true for many fans too, because they're everything that you'd ever want; they're strong and passionate and ferocious and mean and happy. We get to do some great things; we've had shrunken heads with hair, and Korean chests! They're exciting." ()

The appearance of Klingons was, for many years, one of the most popular subjects of discussion among Star Trek fans. It particularly focused on why their foreheads evolved from their smooth look in TOS to their ridged designs in the Star Trek films and later productions. (Star Trek: The Official Starships Collection, issue 53, p. 14) Many comments which  received from readers questioned why the Klingons had changed so drastically, through the years. () Between the release of The Motion Picture and the broadcast of "Trials and Tribble-ations", several fan-devised theories for the discrepancies between the two main forms of Klingons were postulated. (Cinefantastique, Vol. 37, No. 2, p. 40) One suggestion, relayed by Richard Arnold, was that the two variants of Klingon were from different hemispheres of the Klingon homeworld than one another. () The decision to maintain the Klingons' head ridges for Enterprise proved extremely controversial among the fans. () "In fact," Larry Nemecek commented, in 2002, "the Great Klingon Dilemma – smooth versus bumpy, and why? – is the biggest ongoing question mark in Star Trek lore today [....] By now, the parameters to play with [...] have become the most confusing of any Star Trek point." () Nemecek found it one of the two most vexing points of the series' pilot episode,  (the other being the seeming, bizarre nearness of Qo'noS from Earth), though he concluded, "Bumpy-head Klingons, I can deal with." () Even individual Klingon makeup elements (Worf's head, for example) changed from episode to episode. Besides Michael Dorn and Roxann Dawson, other Star Trek cast members who wore the full Klingon makeup include Avery Brooks, Colm Meaney, LeVar Burton, Rene Auberjonois, Tim Russ, Kate Mulgrew, Ethan Phillips, and Scott Bakula. John Larroquette once referred to the Klingon forehead design as "a crab." ( #138, p. 25) Dorn has heard many similar nicknames, ranging from "Turtlehead" to "Speed Bumps". Actress Telma Hopkins, a friend of Dorn's, used the term "Old Intestine Head" and talk show host Arsenio Hall, on one of his first ever shows, likened a set of Klingon cranial ridges to a pair of Human buttocks. ()

Following the return of Kor, Koloth and Kang in , fans wanted those Klingons to return, despite Koloth and Kang dying in the aforementioned episode. "Of course, a lot of them have speculated about how they could bring us back together again – such as the fact that maybe we weren't completely dead because we have two hearts," acknowledged William Campbell. He tended to think it wouldn't be surprising if the trio of Klingons did indeed somehow make a comeback, despite this not ultimately happening. ()

In the audio commentary for "Reunion", Brannon Braga realizes that he and Ron Moore were responsible for killing off K'Ehleyr in that installment as well as Lursa and B'Etor in Generations, somewhat comedically observing, "We're not very nice to Klingon women."

Most actors who played Klingons relished the roles. () Concerning the appeal of such a part, Spice Williams confided, "It's fun to play the bad guy sometimes, to have a licence to take on a character that's just rude, crude, spits and belches... and shoves and 'Qapla', you know, and that rowdiness." ("That Klingon Couple",  DVD & Blu-ray) Patrick Massett and his wife, Marybeth Massett, played one Klingon each: TNG recurring character Duras, and Parell in . Over the years, actors Vaughn Armstrong, John Larroquette, Charles Cooper, Scott Leva, John Kenton Shull and J.G. Hertzler portrayed multiple Klingons each. In addition, Armstrong and Larroquette both separately imagined, at one point, differently aged Klingons. "They had all these warlike ridges and body armor, and I could just picture them in the backyard as children playing with a goat," Armstrong envisioned, "smacking their foreheads up against the goat's or against each other." () In a jestful manner, Larroquette imagined elderly Klingons, describing "a couple of old Klingons at the Old Klingon Home." ( #138, p. 25)

Herschel Sparber, who appeared as Federation President Jaresh-Inyo in fourth season DS9 two-parter  and , had a life-long ambition to play a Klingon on Star Trek. "I always thought I would get on as a Klingon because I'm 6'9 and weigh 300 pounds," he explained. When Sparber auditioned for the role of Jaresh-Inyo, the idea of keeping the actor in mind for a Klingon part was temporarily considered by Casting Director Ron Surma, who told Sparber, "I'll probably bring you back as a Klingon or something." After instead portraying Jaresh-Inyo, Sparber retained his Klingon-related dream, mentioning in an interview, "It would be great to come back as a Klingon." ("The Keeper of Paradise", Star Trek: Deep Space Nine - The Official Poster Magazine, No. 10) However, this never happened.

Similarly, Simon Billig, who later appeared as VOY recurring character Hogan, originally auditioned for the role of a Klingon in Star Trek: Deep Space Nine (in ), though he wasn't cast in the part. (TV Zone, Issue 93, p. 30)

The Klingon emblem was designed by Matt Jefferies, also responsible for the very first visual representation of the Klingon script . He was interested in making it a simple shape which would be instantly recognizable. () The only time the symbol is seen in the original series is in , and the high spire is actually facing right, not straight up as the subsequent versions are. Also, on the original Klingon ship model (the camera angles never showed it on the series), it was facing to the right there as well. It was probably meant to be that way originally, but series executives and concept designers likely found it looked better pointing straight up. It was not the first Klingon emblem shown on screen. An earlier version was featured in the original Klingon episode , seen as a letterhead on a proclamation Kor was reading, as well as a wall ornament in his office on Organia. It was Jefferies' more aggressive-looking design, however, that stuck for the remainder of the franchise; the original symbol was only ever shown in "Errand of Mercy".

The infamous Klingon saying, "Today is a good day to die," actually originated from the Lakotan warrior Crazy Horse, while the proverb, "Revenge is a dish best served cold," paraphrased by Khan in Star Trek II, is actually a saying of the Pashtun people of South Asia.

Whereas After Trek host and Star Trek fan Matt Mira initially expressed puzzlement at the DIS Klingons, Sarek actor James Frain was impressed by the series' Klingons. "They, first of all, have got a very advanced sense of fashion, which also blends with their whole world behind them. Aesthetically, I think they're pretty cool." However, Frain also joked that the species has "British teeth" which he humorously reckoned makes French kissing awkward. Mira likewise jokingly speculated that both French kissing a Klingon and getting clipped by a Klingon while walking past one in a corridor would be extremely painful. ()

 Real-world political analogies 
While Ronald Reagan was visiting the set of  in , someone asked him what his opinion of the Klingons was. He replied, "I like them. They remind of Congress." ()

In 2002, , managing editor of , advocated hiring Klingons as financial stock analysts. Remarking on some then-current stock analysts who apparently had been misleading the public about the value of their share choices, Wastler urged, "Make them Klingon. Then they would be compelled to stand by their words, even fight to the death to defend them... that would really put some meaning into stock recommendations." ()

On 10 January 2007, Congressman  made a speech, on the House of Representatives floor, referring to George Bush's staff as Klingons, with regard to the Iraq War. Wu, an admitted fan of Star Trek, said he was making a reference to the title of James Mann's recent book Rise of the Vulcans: The History of Bush's War Cabinet (). In the book, Mann writes that "Vulcans" is a nickname that President Bush's foreign policy advisory team in the 2000 campaign gave itself, originating from a large statue of the Roman god Vulcan in Bush adviser Condoleezza Rice's hometown of Birmingham, Alabama.

Wu said that – unlike "the Vulcans of Star Trek", who "make decisions based on logic and fact" – Rice and her cadre behave more like the warlike Klingons, saying, "There are Klingons in the White House." Wu continued that – unlike "real Klingons", who are also known as fierce warriors – those in the White House "have never fought a battle of their own." He concluded, "Don't let faux Klingons send real Americans to war."

On 16 January 2007, comedian Jon Stewart dedicated a short segment of The Daily Show with Jon Stewart'' to talk about the speech Wu had made. Stewart was joined in this discussion by Leonard Nimoy and George Takei (Spock and Hikaru Sulu, respectively). In the discussion, Nimoy stated the analogy was weak, citing that – while Klingons are warlike – they adhere to a strict code of honor.
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