Ash Tyler, formerly known as Voq, was a 23rd century Klingon warrior who underwent the choH'a', an extreme, agonizing surgery so that he would appear to be Human during the Federation-Klingon War. His DNA and memories were somehow spliced with captured Starfleet officer Lieutenant Ash Tyler in the experimental procedure, making him an artificial hybrid. This procedure was extensive enough that his entire body appeared Human, and internal scans proved his organs had been modified as well; anatomically, he was completely Human. His mission was to become a sleeper agent, and by the time the process was complete, Tyler's personality had completely subsumed Voq's.
As Ash Tyler, he became the chief of security of the USS Discovery, where he began a relationship with Michael Burnham. Voq's memories began to resurface after his compatriot L'Rell was captured by the Discovery, but the Ash Tyler persona's attraction to Burnham prevented them from being restored completely. However, after the Discovery was transported to the mirror universe, Voq met his counterpart, which caused his full Klingon personality to be restored. Voq unsuccessfully attempted to murder Burnham before being detained by the Discovery crew. Later, surgery caused the two personalities to merge together, leaving the surviving personality, that of Tyler, guilt-ridden and ashamed. Ultimately, when L'Rell left to take leadership of the Klingon High Council, Tyler chose to leave the Discovery to aid both the Federation and the Klingon Empire, having decided he was no good for either side alone. (DIS: "Into the Forest I Go", "The Wolf Inside", "Will You Take My Hand?")
Under the guise of Ash Tyler, Voq believed he was held captive for 227 days, almost seven months. His cellmate during his captivity was Harcourt Fenton Mudd. During his time with Mudd, he listened to his story of how he robbed a bank on Betazed. He was "rescued" along with Captain Gabriel Lorca by the USS Discovery, all according to L'Rell's plans. (DIS: "Choose Your Pain", "Magic to Make the Sanest Man Go Mad")
A week after this, Captain Lorca appointed "Tyler" as his new chief of security aboard the Discovery. Captain Lorca was impressed by his skill piloting a stolen Klingon raider during their escape, as well as his impressive marksmanship in Discovery's holographic combat simulator. (DIS: "Lethe")
"Tyler" appeared to have suffered from severe post-traumatic stress disorder as a consequence of rape, torture, and medical experimentation inflicted upon him during his imprisonment by his Klingon "captor", L'Rell. (DIS: "Into the Forest I Go") Furthermore, he harbored an internal rage towards Klingons, wanting to hurt them the way they hurt him. (DIS: "Si Vis Pacem, Para Bellum") During his mission with Burnham to place sensors in the Klingon Ship of the Dead, "Ash" encountered L'Rell in a room of corpses, and subsequently lapsed into catatonia. He was coached back to a conscious state by an injured Admiral Katrina Cornwell, who was a prisoner on the ship, and was able to defeat incoming Klingon warriors who were closing on their position. L'Rell was subsequently taken prisoner and transferred to Discovery's brig. (DIS: "Into the Forest I Go")
"Tyler" was still haunted by nightmares and flashbacks from his violations, and what was later revealed to be his surgical transformation from Voq to the Human form of Tyler. He took solace in his burgeoning romantic relationship with Burnham, who had shared trauma from the loss of her parents, her transient death, and the events from the Battle of the Binary Stars.
When the Discovery found itself in the mirror universe, "Tyler", who was experiencing nightmares of surgery being performed on him, went to confront L'Rell in the brig. L'Rell recited a Klingon prayer to him, which seemed to trigger a reaction. Disturbed by this, "Tyler" asked Doctor Hugh Culber to perform a medical examination on him to see if he was fit for duty. Culber discovered that, contrary to earlier examinations, his patient's skeletal structure and organs had been surgically altered and that his personality had been overlaid the personality of someone else. Culber said he had to ground "Tyler" because he was not sure that he was who he claimed to be. In response, "Voq" became self-aware and broke Culber's neck before accompanying Burnham and Lorca on a mission to the ISS Shenzhou. (DIS: "Despite Yourself")
While aboard the Shenzhou, Tyler and Burnham were able to gain the trust of a rebel council charged with leading the rebellion against the Terran Empire, which included Sarek and Voq. Listening to the mirror Voq speak was enough to trigger dormant memories in Tyler's mind, which awakened the truth in him that he was, in fact, Voq himself. Having reasserted his Klingon personality, he physically attacked his counterpart, but was defeated in combat. Since Sarek confirmed, through the use of a mind meld, that Burnham's motives were altruistic, she and Tyler were allowed to return to the Shenzhou, where Burnham confronted him in her quarters and learned the truth of his Klingon origins. "Tyler" attacked Burnham and planned to kill her but was thwarted by the intervention of Saru. Facing execution for apparently attempting to kill the ship's captain, per standard Empire orders, "Tyler" was sentenced to be beamed into space. Burnham, however, operated the transporter herself to ensure that "Tyler" could be quickly beamed aboard the Discovery. She had hidden stolen files about the USS Defiant on his person, which the Discovery crew planned to use to return to their universe. Once aboard, "Tyler" claimed that Burnham should have left him to die, but Saru quickly reminded him that was not in the tradition of Starfleet. (DIS: "The Wolf Inside")
"Tyler" was confined to the medical bay where Dr. Pollard and her medical team examined him; their scans confirmed that he was Human, even with "Tyler" displaying enhanced strength. "Tyler" then asked Saru for help, for which Saru turned to L'Rell, who revealed that Voq was given Tyler's personalities and memories in order to infiltrate Starfleet as a spy. Upon seeing "Tyler" in pain, L'Rell agreed to help him, performing a procedure which removed Voq's personality and left Tyler's personality in control – L'Rell marking Voq's passing with the traditional Klingon ritual. (DIS: "Vaulting Ambition")
Upon his recovery and Discovery's return to their universe, Tyler, with Voq's memories, told Saru how Voq agreed to undergo the choH'a'. Despite this revelation, Tyler was accepted by his fellow crewmates such as Cadet Tilly and Lt. Detmer. (DIS: "The War Without, The War Within")
After the war's conclusion, Tyler decided his place was on Qo'noS, helping L'Rell maintain her hold on power. However, his human appearance proved to be a political liability. L'Rell initially protected Tyler, but when Kol-Sha discovered the infant son of L'Rell and Voq, she decided (at the prompting of Section 31 agent Philippa Georgiou) to falsify the deaths of both the child and Tyler/Voq. Tyler and the baby were spirited away from Qo'noS by Section 31; the baby was left to be raised anonymously by the monks of Boreth. Tyler was recruited by Section 31. (DIS: "Will You Take My Hand?", "Point of Light")
As a Section 31 agent, Tyler was assigned to liaison with Discovery in their investigation of the Red Angel and the search for Spock. In that position, he was distrusted by Captain Christopher Pike. (DIS: "Saints of Imperfection", "Light and Shadows")
After Gabrielle Burnham was identified as the Red Angel, Leland ordered Tyler to help him steal the Sphere data from Discovery. However, Leland had actually been taken over by Control who was attempting to take the data for itself and Georgiou warned Tyler after deducing the truth. Tyler betrayed Control who severely wounded him. Tyler managed to broadcast a warning about Leland to Discovery and then fled from the NCIA-93 in an escape pod before it jumped to warp. Tyler's escape pod was detected by Discovery who rescued him. (DIS: "Perpetual Infinity")
After another red burst appeared over Boreth, Tyler contacted L'Rell to arrange safe passage and revealed to Burnham that the planet was the home of Voq and L'Rell's son. Tyler argued with L'Rell about the mission, but she refused to allow him to beam down personally as it endangered the life of their son. The two argued before Pike volunteered to go down instead. While Pike was gone, Tyler and L'Rell recognized the less than ideal circumstances of their reunion and the truth about their relationship: Tyler would always be in love with Burnham like she would always be in love with Voq whom Tyler no longer was. However, while L'Rell no longer wholly recognized her former lover, she understood that like herself, Tyler would do anything to protect their son. After his return, Pike revealed to the two that he had met their son Tenavik who had asked Pike to return Voq's Torchbearer pin to Tyler, no longer needing it to guide his way. (DIS: "Through the Valley of Shadows")
When the Discovery chose to travel to the 32nd century in order to keep the Sphere data out of Control's hands, Tyler chose to remain in the present to continue his work for Section 31, considering it to be important. Tyler departed shortly before the Battle near Xahea, only to return with L'Rell and a fleet of reinforcements to help the Discovery and the USS Enterprise against the Section 31 drone ships. From the bridge of a Klingon cleave ship, Tyler watched as Discovery successfully made it through the wormhole.
Following the defeat of Control and the departure of Discovery, Tyler became the acting commander of Section 31. At a debriefing for the events surrounding the destruction of Control, Tyler was offered a promotion to Commander and the position of permanent head of Section 31. Due to Tyler's unique experiences and history, Starfleet came to regard him as the perfect candidate to lead the controversial organization, an offer that Tyler accepted after being reassured that Starfleet had completely destroyed Control. (DIS: "Such Sweet Sorrow", "Such Sweet Sorrow, Part 2")
- "Choose Your Pain" (Season 1)
- "Magic to Make the Sanest Man Go Mad"
- "Si Vis Pacem, Para Bellum"
- "Into the Forest I Go"
- "Despite Yourself"
- "The Wolf Inside"
- "Vaulting Ambition"
- "The War Without, The War Within"
- "Will You Take My Hand?"
- "Point of Light" (Season 2)
- "Saints of Imperfection"
- "The Sound of Thunder"
- "Light and Shadows"
- "If Memory Serves"
- "The Red Angel"
- "Perpetual Infinity"
- "Through the Valley of Shadows"
- "Such Sweet Sorrow"
- "Such Sweet Sorrow, Part 2"
"Ash Tyler" was portrayed by actor Shazad Latif.
Originally, CBS announced in December 2016 that T'Kuvma's protégé, then named "Kol", was to be played by Shazad Latif. In the final version of the series, Latif went on to portray "Ash Tyler" and T'Kuvma's protégé was renamed "Voq", while the name Kol was given to a leader of a rival Great House.  Ultimately, however, it turned out that the character of Ash Tyler was actually a construct for Voq to infiltrate Human society.