A History of the Star Trek Mirror Universe

Lauren Gallaway
TV Star Trek
TV Star Trek Streaming Netflix

As of Episode 10, Star Trek: Discovery takes place in a mirror universe. This mirror universe is run by the Terran Empire instead of the Federation. This Empire is ruled by a ruthless emperor and all other races are considered rebels. When Burnham, Lorca, Tilly, and the rest of the Discovery arrive, they quickly had to change their clothes, attitudes, and ranks to blend into this new totalitarian Federation.

What’s interesting about this turn on the show is that almost every other Star Trek show has ventured into the universe at one point. It first happened on Star Trek: The Original Series on October 6, 1967. The episode was called “Mirror, Mirror” and placed part of the Enterprise crew in this new universe. There were also multiple Deep Space Nine episodes that took place here. Let’s take a look at these episodes and if they can tell us where Discovery might go next.

“Mirror, Mirror”

In the Star Trek: The Original Series episode,”Mirror, Mirror,” Kirk, Scotty, Bones, and Uhura beamed onto the Enterprise in the mirror universe. They switched places with their doubles and had to assume their roles. This episode first introduced the concept of the Terran Empire. The Empire used an arm salute, had a gold sword insignia and believed humans should rule the galaxy. They achieved promotion through assassination and are ruthless in their pursuit of power. While in this universe, Kirk had a profound influence on Terran Empire Spock — who went on to bring reforms to the Empire after the original crew returned home.


Deep Space Nine first visited the mirror universe in the episode “Crossover.” When Kira and Bashir returned to the station after a mission, they came face to face with Kira’s double — a ruthless Bajoran leader who understood the concept of the mirror universe. “Perhaps you’d recognize the name Kirk.” Kira’s double explained what happened in the TOS episode “Mirror, Mirror,” and how Kirk’s influence on Spock led to reforms in the Terran Empire. As the Terran Empire grew weaker, the Klingon/Cardassian Alliance grew in its place. While in this universe, Bashir inspired a human uprising against the Alliance, which is further explored in “Through the Looking Glass.” Kira and Bashir eventually made it home and explain the mirror universe to the DS9 crew.

“Through the Looking Glass”

Deep Space Nine returned to the mirror universe in the Season 3 episode “Through the Looking Glass.” The mirror universe version of Miles O’Brien abducted prime timeline Sisko and took him back to the mirror universe. Since Kira and Bashir’s visit, O’Brien had perfected how to travel between universes via the transporter. O’Brien explained that he was fighting a rebellion against the Klingon/Cardassian Alliance and that his Sisko died fighting. O’Brien convinced Sisko to help them by saving the life of his former wife Jennifer. This episode holds a lot of emotional weight for Sisko because in his universe, Jennifer died many years prior during the Battle of Wolf 359.

Deep Space Nine made three more journeys into the mirror universe in the episodes “Shattered Mirror,” “Resurrection,” and “The Emperor’s New Cloak.”

“In a Mirror, Darkly: Part 1 & 2”

Star Trek: Enterprise had a two-part mirror universe episode called “In a Mirror, Darkly.” This episode took place entirely in the mirror universe with Terran Empire Enterprise crew members. When a ship from the future appeared in this universe, Archer tried to weaponize it. He and most of the Terran Enterprise crew died trying to get hold of the ship. Hoshi named herself Empress of the Terran Empire and became Captain of the USS Defiant. It is this Defiant ship that is mentioned in Star Trek: Discovery episode “Despite Yourself.” The episode took place before the TOS episode “Mirror, Mirror.”

“Despite Yourself”

Michael Burnham Tilly

“Despite Yourself” is the 10th episode of Star Trek: Discovery. When the Spore Drive went haywire, it sent the Discovery through to the mirror universe. The crew was unaware of the existence of this mirror universe, since the events of “Mirror, Mirror” had not happened yet. They did find, in their ship’s logs, something about a USS Defiant making its way from the future to this universe. This is the ship that Terran Empire Archer was trying to salvage in “In a Mirror, Darkly.”

Lorca discovered that he had been working with Vulcan rebels and that Burnham tried to get him killed. Tilly discovered that she was the Terran Empire Captain of the Discovery and that Burnham was the Captain of the Shenzhou. The crew of the Discovery had to change their uniforms, just like Kirk, Scotty, Bones and Uhura did in “Mirror, Mirror.” Burnham also killed her first officer, much like Archer tried to kill his Captain in “Through a Mirror, Darkly.” They are going to have to blend in until they can figure out how the Defiant arrived in this universe.

What’s unique about Discovery venturing into the mirror universe is that they aren’t taking a one-episode trip. Some of their crew didn’t switch places with their other selves. Their entire ship — including their Spore Drive — is in the mirror universe. Burnham, who has always wanted to be Captain, finally gets her chance. She’s going to have to avoid giving in to her more violent nature for days, maybe even weeks, until the Discovery can get home. This is going to be a huge temptation for her. Tyler is also experiencing strange PTSD and surgery flashbacks and his torturer L’Rell is on board. This is not going to be an easy trip down the rabbit hole and Alice — our fearless Burnham — is going to have to keep her wits about her if she and Discovery are going to make it back home.

Star Trek: Discovery airs Sundays at 5:30PST/8:30EST on CBS All Access and globally on Netflix the following day.

Lauren Gallaway
TV editor at FANDOM. Creator of The Marvel Report. Journalist, Comic-Con reporter, Podcaster.