Una Chin-Riley
Commander Una Chin-Riley, commonly known professionally as Number One, was a female Illyrian Starfleet command division officer who lived during the mid-23rd century. Through the 2250s, she served aboard the  as Christopher Pike's first officer and helmsman. (; )

Early life 
Chin-Riley was born on an Illyrian colony in the early 23rd century. As a member of the Illyrian species, Chin-Riley was genetically enhanced. Early on in life, she dreamed of joining Starfleet; however, due to the Federation ban on genetic engineering, she had to hide her true nature and history. ()

Starfleet career

Early assignments 
By the mid-23rd century, Chin-Riley joined Starfleet and, as an ensign, was assigned to the  During her assignment aboard the "King Junior", she was involved in the rescue of La'an Noonien-Singh. () 

While questioning Ensign Zier, Chin-Riley sympathized that she, too, was once an ensign, and understood being nervous. ()

At some point in her career, Chin-Riley served aboard the  alongside her future commanding officer Christopher Pike. (, )

According to Pike, Chin-Riley had a habit of jumping from department to department, although she claimed that it only happened once. ()

USS Enterprise 
Upon her assignment to the , she witnessed a triple-mode high-amplitude Delta Scuti star on her first deep-space cruise that took her within a half light year of 99 Pegasi. ()

2254 

By 2254, she served under the command of Captain Christopher Pike. As well as being the ship's helmsman, Una served as its first officer, and went professionally by the name "Number One". (, )

In 2254, Number One greeted Ensign Spock, who joined the crew of the Enterprise after departing from Starbase 40. She encouraged him to barrage her with questions, which he returned in kind. While talking, however, the two were trapped in a turbolift, where they bonded and Una gave advice to the young officer before they were rescued by Lieutenant Amin. ()

At the time, she was considered one of the most experienced members of the crew. According to the Talosian magistrate known as The Keeper, she had "the superior mind and would produce highly intelligent children", adding that, "although she seems to lack emotion, this is largely a pretense. She has often had fantasies involving [Pike]." ()

With Pike kidnapped by the Talosians, Number One led the effort to rescue him, first by unsuccessfully attempting to use a laser cannon to blast open an entry to a Talosian underground lair where Pike was being held, and then by using the transporter in an attempt to infiltrate this lair. Number One was subsequently kidnapped, along with Yeoman Colt, for the purpose of providing Pike with a mate with whom he could procreate. In response to this, Una set her laser pistol to overload, telling the Talosian Keeper that it was wrong to keep a colony of Humans as slaves, and that they would rather die. This, combined with an examination of the Enterprises historical records, convinced the Talosians that Humans' unique hatred of captivity made them nonviable subjects, and they were subsequently allowed to return to the Enterprise. ()

Footage of her experience aboard the Enterprise under Captain Pike during the original visit to Talos IV, from thirteen years prior, was transmitted from that planet during Spock's fictional court martial aboard the same ship in 2267. ()

2256 
Like most of the Enterprise crew, Number One sat out the  which like everyone else aboard the Enterprise took its toll. ()

2257 

In 2257, she remained with the ship while it underwent major repairs that year, but briefly visited Pike aboard the  to provide him with information on Spock's recent escape from Starbase 5. The two officers sat and talked briefly as Number One sat down to a meal in the mess hall. During their conversation, Una admitted that she went through unofficial channels to obtain the information, noting that the entire situation was extremely odd. Una stated plainly that she was not going to let Spock go without a fight and Pike noted that as usual they both were in agreement. Before they parted she warned Pike to be careful and Pike told her the same. She returned to the Enterprise shortly thereafter. ()

2258 

In 2258, following the mission to get a time crystal from the monastery on Boreth, Christopher Pike asked R.A. Bryce to send a message to the Enterprises XO, Number One, to have the Enterprise rendezvous with the Discovery to take on the Discoverys crew. ()

After the disappearance of the Discovery, Pike, , and Number One were debriefed at Starfleet Command in San Francisco. Following the debriefing, Number One and the others who knew of the Discoverys fate were sworn to never speak of the Discovery or its crew again.

After a hundred and twenty four days of repair, Number One, was still aboard the Enterprise as it traveled to Edrin II. ()

2259 
In 2259, the Enterprise returned to Earth for scheduled maintenance. 

Because she did not deal well with downtime, Number One was assigned to command the  and initiate a first contact mission to Kiley 279 after Starfleet detected signs of warp drive on the planet. However, the Kiley had in fact developed a warp bomb based on observations made from the battle near Xahea. The Kiley reacted negatively towards the first contact overtures and Number One, as well as two other members of the Archers crew were held captive by the Kiley. 

After Number One and the Archer crew were rescued by Pike and an Enterprise away team, Number One returned to her post as first officer of the Enterprise. ()

When the Enterprise was infected by a light virus, she proved to be the only person immune to it, due to undisclosed, illegal genetic modifications that she, like most Illyrians, had. While she could not pass antibodies on directly to the crew, she was able to engineer a situation where she could induce the same antibodies in La'an Noonien-Singh, which could then be used to save the others. ()

When an alien consciousness from the Jonisian Nebula brought the fairy tale The Kingdom of Elysian to life on the Enterprise, Una was used for the character of Z'ymira the Huntress. Una didn't remember the events after the ship was returned to normal. ()

While Captain Pike resolved to protect her from Starfleet, she was arrested a few months later when her illegal genetic status was revealed. When a team of officers arrived to arrest her, Captain Pike moved to defend her by breaking the grip of the security officer who had taken hold of her. Una warned him not to fight back as she had known such an outcome could happen. Captain Pike vowed that he would fight on her behalf. ()

Alternate timelines and realities
In an alternate timeline where Pike was able to avoid his crippling fate, he asked La'an Noonien-Singh about Una after being transported to 2266 from 2259. La'an told him that Una wasn't allowed to have contact with anyone. Spock later revealed that in this timeline, Una had been locked up in a Federation prison colony for nearly seven years for her illegal modifications. ()

Personal interests 
Chin-Riley secretly enjoyed the music of Gilbert and Sullivan. When trapped in a turbolift with Spock on his first day on the Enterprise, she sang "I Am the Very Model of a Modern Major-General", but ordered Spock to forget it. ()

She also enjoyed spicy food. When she met Pike on Discovery, she ordered a cheeseburger and french fries with habanero sauce. () 

Her comfort food, however, was strawberries. ()

Physiology 
As a member of the Illyrian species, Chin-Riley was genetically enhanced as a child. Her physical strength was greatly improved, allowing her to carry a grown person with no visible effort, while her immune system could literally burn out infectious agent from her body without having to rely on antibodies. ()

Key dates 
 Prior to 2254: 
 Assigned to the 
 Assigned to the 
 Assigned to the  under Captain Christopher Pike as first officer and helmsman
 2256–2257: Along with the rest of the Enterprise crew, sits out the 
 2257: Travels to the  to update Captain Pike on the status of Spock and the Enterprise
 2258: Takes part in the Battle near Xahea
 2259: 
 Assigned to the 
 Reassigned back to the Enterprise as first officer
Arrested by Captain Batel after it became known she was Illyrian.

Appendices

Appearances

Background information 
Number One was originally portrayed by Majel Barrett in the  pilot, "The Cage", but credited as M. Leigh Hudec for her subsequent archival appearance featured in both episodes of "The Menagerie". When her character was reintroduced for , and its subsequent spin-offs, she was portrayed by Rebecca Romijn.

In the original version of the series outline Star Trek is... (as reprinted in The Making of Star Trek, pp. 22-30), Number One was initially described as "a glacierlike, efficient female who serves as ship's Executive Officer." (The Making of Star Trek, p. 24) A more detailed description of the character from exactly the same document stated; 

The Executive Officer
Never referred to as anything but "Number One", this officer is female. Almost mysteriously female, in fact – slim and dark in a Nile Valley way, age uncertain, one of those women who will always look the same between years twenty and fifty. An extraordinarily efficient officer, "Number One" enjoys playing it expressionless, cool – is probably Robert April's superior in detailed knowledge of the equipment, departments, and personnel aboard the vessel. When Captain April leaves the craft, "Number One" moves up to Acting Captain. (The Making of Star Trek, p. 29)

In the scripts of "The Cage", Number One was described as "Female, slim and dark in a Nile Valley way, age uncertain, one of those women who will always look the same between the ages of twenty and fifty [....] Almost glacier-like in her imperturbability and precision. From time to time we'll wonder just how much female exists under that icy facade." She was also scripted to be slightly more wary of J.M. Colt than she is in the final version of the episode, such as being initially reluctant about allowing her to join a landing party assigned to rescue the captain. 

Number One was dropped from the series as NBC executives did not respond well to her character. Reactions to her in the screen test of "The Cage" were also poor (by the women more negatively than the men, according to Gene Roddenberry). Her highly logical, steel-trap mind was given to the character of Spock in  and maintained there onward.

Although Majel Barrett-Roddenberry was credited as Majel Barrett in the unaired episode "The Cage", she was credited as "M. Leigh Hudec" – Barrett's birth name – in the televised two-part episode  and , because the production team was endeavoring to hide from NBC the fact that the actress, not to be signed for either the second pilot or the regular show as had been demanded by the network, had actually returned to  as the recurring Nurse Christine Chapel by Gene Roddenberry's doing. (Inside Star Trek: The Real Story, 1997, pp. 223-224; These Are the Voyages: TOS Season One, 1st ed, pp. 25-27) An unintended ironic twist in Star Trek history was that when Roddenberry surreptitiously brought the natural brunette Barrett back on the Original Series, he had her also disguised as a blonde to mislead the NBC network executives, who adamantly did not want her back on the show, whereas the natural blonde Romijn had to have her hair dyed to have her appear as the brunette Number One in Discovery.

Regarding Number One's rank in the pilot, and in later Star Trek incarnations, it was rare for a lieutenant to serve as the first officer of a starship. The likely reason for this was that, when Gene Roddenberry first created Star Trek, the first rank structure he employed was based on the system used in the 18th and 19th century British navy, in which a ship's second in command was generally a first lieutenant in the sense of the most senior lieutenant, rather than 20th century naval ranks we have come to associate with Starfleet. In the character's subsequent appearances in  and , she holds the rank of lieutenant commander.

In an interview with TrekCore, the co-writer of  and  third season co-showrunner Michelle Paradise confirmed that Christopher Pike called Number One "Una" in that episode.  This is one of several names which had been used for this character in non-canon material. Subtitles on Netflix and the second season Blu-ray release misspelled it as "Noona" (the Netflix subtitles have since been corrected), while the CBSAA captions say that he merely said "and, uh..." while transitioning to a question directed at Admiral Cornwell. Dialogue and PADD graphics in the  episode  definitively confirm that Number One's name is "Una," and that she insists on being addressed as "Number One".

According to The Autobiography of Mr. Spock, Una's full name is Una Chin-Riley, a fact later revealed in the Strange New Worlds premiere episode "Strange New Worlds".

Apocrypha
In the Marvel Star Trek: Early Voyages comic book series, this character was named Lieutenant Commander Robbins. Her first name was interrupted by other dialogue, but starts with "Eure-."

The  Vulcan's Glory, by  writer D.C. Fontana, suggested this character's moniker was not simply a nickname or title – she was an Illyrian who was called "Number One," as the best intellect among her generation. The novels The Children of Kings and Child of Two Worlds explain that Number One does have a given name, but it's difficult to pronounce for non-Illyrians; the former suggests that she liked to be called by this name rather than her own as it enabled her to maintain a professional relationship with her captain. The novel The Enterprise War describes her as having been raised in Illyrian colonies and thus, while not actually being Illyrian herself, having adapted much of that species' emotional self-control. Her actually being Illyrian and raised in an Illyrian colony was confirmed canon in .

In the novel Captain to Captain she is referred to as "Una". The novel explained that she had adopted the name Una as far back as her Academy days, due to her real name being all but impossible to pronounce. The name "Una" was also used in the  novel Desperate Hours and was subsequently used in  and .

Star Trek II: Biographies gives her real name as Leigh Hudec (after "M. Leigh Hudec", the name under which Majel Barrett was credited in The Cage).

Peter David's New Frontier series of novels had a character named "Morgan Primus" who was an immortal like Flint (from ) and was the mother of Robin Lefler. It is hinted that she and Number One are the same person.

In the Captain's Table  Where Sea Meets Sky, Number One was given the last name "Lefler" (an allusion to Robin Lefler).

The early days of Number One were chronicled in the IDW Publishing miniseries Star Trek: Crew.

In the IDW Publishing comic Star Trek: Romulans - Schism, she is a commodore in command of the  testing the cloaking device stolen from the Romulans during the events of . No name is mentioned.

In the miniseries Star Trek: Leonard McCoy, Frontier Doctor, Number One was promoted to admiral in the 2270s and continued to command the Yorktown. 

In the first issue of the 2013 comic series Star Trek: New Visions, Kirk, Spock, and McCoy report to a commodore who is not named but is clearly Number One and Spock did say it was pleasant to see her again.  

In Who's Who in Star Trek, Number One is said to have been descended from colonists on a planet inhabited by telepathic humanoids who are peaceful. She is described as having entered Starfleet after saving the life of Earth's leader when his shuttle crashed on her planet, he having waived all psychological and physical testing on her behalf. She is also described as having suffered severe injuries just prior to the end of Pike's tenure as captain of the Enterprise, forcing her to retire from exploration and become an instructor at Starfleet Academy.

External links
 
 
 
 

de:Nummer Eins
fr:Numéro Un
Illyrians
Starfleet command personnel
USS Enterprise (NCC-1701) personnel
USS Archer personnel