D. Nhan
Commander D. Nhan was a female Barzan who served as a Federation Starfleet officer in the 23rd century. Aboard the , she traveled to the 32nd century and subsequently assumed responsibility for the  before joining Federation Security.

Early life 
When Nhan chose to leave her homeworld to join Starfleet, her family was devastated. She never imagined Barzan II would join the Federation. ()

Starfleet career

Serving on the Enterprise 
By the late 2250s, Nhan was serving as an engineer aboard the  under Captain Christopher Pike, holding the rank of Commander. Being Barzan, Nhan relied on an augmentation to be able to breathe in the atmosphere maintained aboard Starfleet ships. ()

Serving on the Discovery 

Along with Evan Connolly, she accompanied Captain Pike onto the  when the Enterprise suffered a malfunction. She was also a part of the team that investigated the crashed wreckage of the . ()

Nhan later transferred to the Discovery and served on the bridge crew, later assigned as chief of security. ()

Nhan became suspicious of Airiam when she asked about the Barzan's breathing apparatus. Nhan continued to observe Airiam as Discovery approached Section 31 Headquarters. When Airiam requested to join the away team, Nhan told Pike that she would "look after" Airiam. While Nhan, Airiam, and Michael Burnham were aboard the space station, the Discovery crew learned that Airiam's cybernetic components had been corrupted by Section 31's threat assessment system, Control, in an effort to access the Sphere's data. Nhan and Burnham confronted Airiam, who ripped one of Nhan's breathing augmentations off, leaving her gasping to breathe. Burnham trapped Airiam in an airlock, but hesitated to blow her into space, despite pleas from Airiam and an order from Pike. Nhan ultimately regained consciousness and ejected Airiam into space, killing her. ()

She attended Airiam's funeral afterwards, and later apologized to Burnham for her actions. Burnham assured Nhan that she did the right thing. ()

When it was decided that Burnham would take Discovery forward to the 32nd century to prevent Control from seizing the  data, Nhan volunteered to stay on board Discovery.  Despite knowing that there would be little chance of return, she believed that she owed it to Airiam for the latter's sacrifice. ()

Nhan helped  in neutralizing Leland (who had been reanimated by Control), when Leland boarded the Discovery to take the Sphere data. After the Discovery disappeared from its original timeframe, Nhan, along with the rest of the volunteering crew, was presumed dead by Starfleet, based on the testimonies of the  senior officers. ()

USS Tikhov 
Upon Discovery tracking down Federation Headquarters in the 32nd century, they needed to locate a seed sample from the seed vault ship . Nhan learned that the Barzan joined the Federation in the 25th century, and was responsible in a member rotation for crewing the Tikhov. Nhan, Burnham and Dr. Hugh Culber beamed aboard, allowing Nhan to breathe a Barzan atmosphere, hear the Barzan language, and see a Barzan for the first time since she had joined Starfleet. When the sole surviving Barzan aboard, Dr. Attis, needed to be taken for treatment, Nhan volunteered to serve as her world's representative and crew the Tikhov, with the intention of seeing that Attis' family receive a proper burial on their homeworld. ()

Federation Security 
Nhan remained on Barzan only briefly after completing the mission on the Tikhov, finding members of her family line but feeling unable to connect with them, due to her coming from centuries in the past. By 3190, she had joined Federation Security, which appealed to the Barzan sense of duty above all. She was deployed with a covert task force to contend with the remnants of the Emerald Chain, resulting in several particularly bloody skirmishes. During one mission, she lost half of her team because she hesitated to make what she later felt was the correct decision, but was able to save 115 people.

Following this mission, she was approached by Fleet Admiral Charles Vance, Starfleet's commander in chief, to return to Discovery to oversee the pursuit of wanted fugitives Cleveland Booker and Dr. Ruon Tarka, who stole the prototype for the next-generation spore drive in order to deploy an isolytic weapon to destroy the Dark Matter Anomaly. Due to Captain Burnham's close relationship with Booker, Vance's orders gave Nhan the backing of his full authority to relieve Burnham and stop Booker and Tarka if she believed the captain unable to do so. This led to some tension between the two, particularly after Nhan offered a "last resort" plan to destroy Booker's ship to prevent the use of the isolytic weapon, and became emphatic about using it during the confrontation with Booker within the DMA. Despite her typical black-and-white approach, she was convinced by Burnham to accept a compromise that they both agreed to take to Vance, who approved it. Though the effort failed, Nhan gained a greater appreciation for finding middle ground. ()

Key dates 
 Prior to 2257: Assigned to  as an engineer
 2257:
 Assigned to  as chief of security
 2258: Along with Discoverys crew, travels to the 32nd century
 3189: 
 Arrives with Discoverys crew
 Takes responsibility for USS Tikhov
 3190: Joins Federation Security

Memorable quotes 
"I see where the Federation puts its pennies."
"Do not covet thy neighbor's starship, commander. Besides, we've got the new uniforms."
"And lovely uniforms, they are. Captain."
"Very colorful."
- Nhan, Christopher Pike, Saru, and Michael Burnham, on the Discovery and new Starfleet uniforms ()

"Nhan. Security officer, USS Discovery. SFB534-0679."
"Failure to comply is insubordination."
"I'm sorry."
"Now, how long was the durat–"
"Nhan, D. Security officer, USS Discovery. Throw me in the brig, hologram."
- Nhan and a holographic interrogation officer, on Nhan's refusal to cooperate ()

Appendices

Appearances 
 
  (Season 2)
 
 
 
 
 
 
  
 
 
  (Season 3)
 
 
  (Season 4)

Background information 

Nhan was portrayed by actress Rachael Ancheril. 

When Nhan was aboard the USS Enterprise, she wore a red shirt uniform. However, after joining the USS Discoverys crew she began wearing their signature blue uniform but with a skirt, though her skirt uniform differed from that of  by not showing her legs. She wore black boots that went up past her knees and any time skin between the boots and the end of skirt was seen, that skin was covered by thick black leggings to make it appear like she was wearing pants underneath the skirt.

External link 
 

Barzans
Starfleet operations personnel
USS Discovery personnel
USS Enterprise (NCC-1701) personnel