7 Best Star Trek Mirror Universe Episodes 

We cover the top seven Mirror Universe episodes of Star Trek.

By Chris Snellgrove | Updated

star trek mirror universe

When you get right down to it, there are really two kinds of Star Trek fans: those who enjoy the campy silliness of the Mirror Universe episodes and those who just don’t know how to have fun. We’re assuming that you guys like to have fun, and that means that sooner or later, you’re going to stream some of Trek’s Mirror Universe episodes on Paramount Plus. To help you get right to the good stuff, though, we’ve compiled the definitive list of the best Mirror Universe episodes in the entire franchise.

7. Star Trek: Discovery – “What’s Past Is Prologue”

star trek mirror universe

Star Trek: Discovery has proven to be one of the more controversial Trek shows, especially after they returned to the Mirror Universe back in the first season. However, here’s a take hotter than the warp core that ship barely seems to use: the Mirror Universe episodes were generally some of DISCO’s best.

“What’s Past Is Prologue” provided an exciting and rollicking conclusion to their initial adventures into this hellish alternate dimension. And while it’s fun to see Michael Burnham figure out how to save the day, the real joy of this episode is watching the traitorous Captain Lorca and the villainous Emperor Georgiou at their campy, mustache-twirling best.

6. Star Trek: Discovery – “Despite Yourself”

star trek mirror universe

For better or for worse, Star Trek: Discovery spent an extended time in the Mirror Universe in that first season, and some of the episodes were stronger than others. One of the early standout episodes was “Despite Yourself,” where our crew of heroes had to dress the part of their evil counterparts and engage in a bit of evil roleplaying in order to survive.

This leads to plenty of wonderful fish-out-of-water comedic moments, especially when mousy Cadet Tilly must impersonate her powerful and domineering counterpart “Captain Killy” in scenes that most likely awakened something in more than a few fans. 

5. Star Trek: Deep Space Nine – “Crossover”

star trek mirror universe

Outside of some non-canonical media, Star Trek: The Next Generation never really dabbled in Mirror Universe stuff, so it was the Deep Space Nine episode “Crossover” that officially brought us back to this dark dimension.

In the episode, a wormhole anomaly sends Major Kira and Dr. Bashir away from their familiar universe and into the one that Captain Kirk once visited by accident back in The Original Series. Interestingly, this episode reveals how Kirk’s interference inadvertently led to a universe where humans (or “Terrans”) are secondhand citizens, and Kira and Bashir quickly discover their only way home may be to help kick off an intergalactic Revolutionary War.

4. Star Trek: Deep Space Nine – “Shattered Mirror”

star trek mirror universe

When Star Trek: Deep Space Nine first returned us to the Mirror Universe, they played everything mostly straight (so to speak) except Major Kira, whose Mirror Universe double is just as enthusiastically evil as she is horny for anything that moves.

Conversely, the episode “Shattered Mirror” not only fully leans into the campy, soap opera nature of its villains, but it gives Worf a mirror makeover as a twisted Klingon commander who keeps Garak on a tight leash (quite literally).

Sure, there’s also a touching plot here about Jake Sisko getting to meet his Mirror Universe mother, but the real highlight is the Defiant looking like the Millennium Falcon as it takes on a giant enemy warship. 

3. Star Trek: Deep Space Nine – “Through the Looking Glass”

star trek mirror universe

In the grand tradition of Star Trek: Deep Space Nine showing how our characters keep messing up the Mirror Universe, “Through the Looking Glass” follows up on the Terran rebellion against their alien oppressors that Kira and Bashir helped kick off back in “Crossover.”

When the Mirror Sisko dies, our Sisko must impersonate him long enough to oversee the construction of the Defiant (“Smiley” O’Brien stole the designs the last time he was in our universe). In addition to seeing more fun Mirror versions of our favorite characters, this episode is plenty of fun because it shows Sisko acting as a kind of secret agent on a mission to save an entire universe.

2. Star Trek: Enterprise – “In A Mirror, Darkly”

star trek mirror universe

If you tuned out of Star Trek: Enterprise in its rockier seasons, you probably missed out on the delightful season 4 return to the Mirror Universe with the episode “In a Mirror Darkly.” Unlike all other Mirror episodes, this two-parter doesn’t feature our heroes crossing over, instead effectively showing us what a day in the life of this evil Mirror crew is really like.

The alternate opening credits for this episode are hilarious, and we cheered when it confirmed that the Defiant that Kirk once visited (different from the one on Deep Space Nine) really did get sucked into the Mirror Universe as the old fan theory claimed, and Discovery would later pick up on this decades-old narrative thread.

1. Star Trek: The Original Series – “Mirror, Mirror”

star trek mirror universe

No surprise here: we couldn’t exactly rank all of the Star Trek episodes set in the Mirror Universe without giving the top spot to “Mirror, Mirror,” The Original Series episode that brought us here.

In this episode, Kirk, Dr. McCoy, Scotty, and Uhura experience a freak transporter malfunction that brings them into a dark dimension in which Starfleet is an evil and oppressive empire and in which survival is often a matter of betraying and murdering your colleagues.

Famously, this episode ends with Kirk arguing with a goateed, evil Spock, and the image of him has become such a prominent part of the pop culture landscape that “weird facial hair” is the universal plot signifier for “evil double” in movies and television.