Commander Jett Reno was a 23rd century female Human Federation Starfleet officer. She served as an engineer aboard the USS Hiawatha during the Federation-Klingon War and later aboard the USS Discovery during its investigation of the red bursts.
At some point during the War, she survived the crash landing of the Hiawatha and managed to sustain injured crew members for ten months and eleven days before being rescued by a landing party from the USS Discovery in 2257. (DIS: "Brother")
Assignment to Discovery
At some point following her rescue, she was officially assigned to the Discovery. Around Stardate 1834.2512, when the ship’s computers were infected with a power virus, Reno was assigned to put firewalls around the critical propulsion systems (i.e., the spore drive). While in Paul Stamets‘s engineering lab, Reno verbally sparred with him over the merits of the spore drive. Reno, Stamets, and Sylvia Tilly were trapped in the lab shortly thereafter and had to contend with leaking energy relays and the escape of a multidimensional fungal parasite. Reno and Stamets worked together to save Tilly from the parasite but were ultimately unsuccessful after the lifeform infected them with hallucinogenic spores. (DIS: "An Obol for Charon")
While Discovery was in orbit of Boreth, Reno joined Linus, Joann Owosekun, Keyla Detmer, Nilsson, and Stamets for a meal in the mess hall. She noticed Stamets is in a sour mood. He told her he felt down after failing to find a way to retrieve Gabrielle Burnham from the future or successfully fight off Control. Reno informed him that Pike had left orders for her and Stamets before beaming down to Boreth to prepare to receive a raw time crystal. Reno then playfully bantered with Linus during a game of auto-antonym before observing Hugh Culber entering the mess hall. After Reno expressed surprise that Stamets had not moved on from Culber, Stamets told her to mind her own business. (DIS: "Through the Valley of Shadows")
Later, Reno reported to Sickbay requesting medical assistance. Culber diagnoses her with a mere hangnail, but Reno told him that it was impeding her work, along with an "idiot" who had recently returned from the dead – Culber. He treated her with an analgesic that stings Reno, and she remarked that she could understand why his relationship with Stamets had worked. Culber asked her how long she and Stamets had been friends. Reno remarked that they are not but that she needs Stamets to perform better at his work. After Culber noticed her wedding ring, Reno explained that her wife was Soyousian and acted "totally bananas" while planning the wedding. Reno also revealed her wife died during the Federation-Klingon War and remarked that people such as herself and Culber – more level-headed, pragmatic people – often seem to find partners in people like Stamets or her deceased wife, who are more anxious and fussy. With that, Reno reminded Culber that he was granted a rare opportunity. "You have a second chance, and it may not last forever. Don’t screw it up," she said. (DIS: "Through the Valley of Shadows")
During Discovery's visit to Xahea following the detection of another signal on Stardate 1051.8, Reno attended a meeting to discuss a plan to send the ship forward in time. She astutely deduced that the Xahean queen, Me Hani Ika Hali Ka Po, was working out complex nuclear particle physics calculations while seemingly waving a spoon in the air, building a rapport between the two. After Po described her plan, Reno noted that flowing that much energy through the time crystal would be like getting a drink of water from a waterfall. "It'll work, but then you drown," she explained. Later, Reno joined a group of other Discovery crew in staying aboard the ship with Michael Burnham during the conflict with Control. When Burnham said she could not allow them to put themselves in such danger, Reno replied that they are not asking permission. She then joined Tilly and Stamets to try to speed up charging of the time crystal, which was gaining power too slowly to be ready before Control arrived. They realized the cage housing the crystal was slowing the charge rate. Reno colorfully noted that they could disengage the cage but that "everyone will see visions of the future and their heads will explode." When other options proved fruitless, Reno ordered Stamets and Tilly to leave the room and keep others out. With just minutes before Control was to arrive, she deactivated the cage, speeding up the charge but also triggering visions of the battle to come. (DIS: "Such Sweet Sorrow")
As the Battle near Xahea commenced, Reno informed Burnham that the time crystal needed just over four minutes to finish charging. Burnham asked if she could cut that time in half, but Reno replied that she was unable to break the laws of physics. Once the crystal reached full charge, Commander Saru assigned Tilly to accompany Reno to deliver it to Burnham. The pair met up with Burnham and the others in a corridor shortly after falling debris had severely injured Stamets. Reno handed off the crystal to Burnham and remained behind to repair the damage to the corridor. Reno was present later on the bridge as Discovery followed Burnham, in the red angel time suit, into the distant future. (DIS: "Such Sweet Sorrow, Part 2")
When Discovery arrived in 3189, Reno and the rest of the crew were struck unconscious briefly by tidal forces in the wormhole. The ship's crash-landing on The Colony left Reno complaining about pain in her back. She pointed out that Terralysium, Discovery's intended destination, was not icy, and speculated that the ship's plasma manifold ruptured in the crash, which will require repairing many EPS relays. Despite her injured back, Reno assisted in repairs in engineering, where she partnered with Stamets, himself still recovering from injuries received during the Battle near Xahea. They tracked down the final damaged relay in a Jefferies tube, but Reno's injured back prevented her from being able to access it. Stamets was reluctant given his own diminished state, but Reno gave him a pep talk, saying "Helpless is a shitty feeling, but it is not forever, and it doesn’t make you any less capable." With Reno's remote assistance, Stamets repaired the relay, stabilizing key systems around the ship. (DIS: "Far From Home")
Upon arriving at Federation Headquarters, Reno joined Stamets and others in a corridor looking at the advanced starships in amazement. During interrogation by holographic Starfleet officers, Reno described her rescue from the Hiawatha by Burnham and Captain Christopher Pike, saying sardonically that it was "raining Starfleet officers." She also denied having any knowledge of the Emerald Chain and nonchalantly requested a snack (chips and salsa) and a drink. After Discovery jumped to rendezvous with the USS Tikhov, Reno joined Stamets and Tilly in studying unusual radiation in the vicinity. After Dr. Attis reported seeing a bright light before his family died, Reno and the rest quickly deduced that a coronal mass ejection from a nearby star about six weeks earlier had killed his family. Lieutenant Willa, observing their work, remarked that Reno, Stamets and Tilly had a less-than-professional working relationship. Reno replied that she tried to "raise the bar." She also rebuffed Stamets' statement that they had learned to accept their disfunction. (DIS: "Die Trying")
She later complained to Stamets and Adira Tal that they were taking too much of the ships power trying to locate the source of their distress beacon. Reno snacked on black licorice, which both Adira and Cleveland Booker pointed out violated a rule against consuming food in engineering, though Reno insisted licorice is "not food, it's candy, it's practically an accessory." (DIS: "Terra Firma, Part 2")
Reno was present in engineering when Su'Kal nearly triggered a second Burn. Stamets directed Reno to lock down the warp core's magnetic constrictors in response. Reno later lent her combadge to Adira, who used it to sneak aboard Booker's ship in order to beam down to Theta Zeta. (DIS: "Su'Kal")
Reno was evacuated with most of the rest of Discovery's officers after it was captured by Osyraa and taken to Federation headquarters. She returned after the ship was re-taken and assisted Owosekun in repairing a DOT-23 drone controlled by the Sphere data that had previously saved Owosekun's life. Later, Reno, wearing a dress uniform along with the rest of the senior staff, was present on the bridge when Burnham arrived for the first time as captain. (DIS: "That Hope Is You, Part 2")
"So, unless Hazmat over here is gonna be helping after he cleans up aisle five…"
"M-my name's Gene, actually."
"I've already forgotten that."
"Helpless is a shitty feeling. But it is not forever, and it doesn't make you any less capable."
"Hugh, thanks. Jett, thanks for nothing."
"Back at you, bobcat."
"I don't know, I'm on drugs."
Jett Reno was portrayed by Tig Notaro. She is referred to as "Denise Reno" on StarTrek.com. During a 28 January 2019 appearance  on Conan O'Brien's talk show Conan, Notaro explained that the character had originally been presented to her as "Denise Reno". She recalled that she had replied, "Can't we, like, take it up a notch?" According to Notaro, she then recommended the name "Jett" as a tribute to American rock singer Joan Jett. Notaro admitted during a November 2020 appearance on the Fitzdog podcast that her character's name did end up sounding like former United States Attorney General Janet Reno. 
During the O'Brien interview, Notaro noted that the role requires her to act alongside pyrotechnics and to perform some stunts. She also confessed to having a problem remembering the technobabble dialogue. "As much as I love the show… I'm terrible at the dialogue on the show. I'm really bad," she admitted. 
On the Fitzdog podcast, Notaro said she has been friends with Alex Kurtzman since moving to Los Angeles 22 years prior and so he found her a spot on the show. However, Notaro said she was uninterested in a full-time role. "I'm not looking to become a full cast member but I enjoy the world, and I enjoy the cast and crew, and I think what I have going on is kind of perfect." Notaro also revealed she forfeited some appearances in the show's fourth season over concerns about having to fly to Toronto for filming during the COVID-19 pandemic. But she said further filming will occur in May 2021 and that she hopes to participate, even if she has to drive the distance.