I see many mentions to another universe in Star Trek questions, but I've never actually remember seeing an episode of Star Trek that dealt with this other universe. I've watched all of TNG and all of VOY and nothing in there seems to match up with whats being referenced.

What episodes do I need to watch to familiarize myself with this plot element?

  • 2
    Do you mean the one with beards and one Spock, or the one with no beards and two Spocks?
    – user1030
    May 8, 2012 at 18:35
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    Is there one with two beards one Spock? May 8, 2012 at 18:44
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    @KevinHowell Perhaps the primary universe?
    – Izkata
    May 8, 2012 at 22:39
  • Why the downvote? May 9, 2012 at 9:47
  • 3
    I didn't downvote (and don't plan to), but I'm guessing that of the 5 live action series, the only series where the mirror universe is not featured, are the ones you've seen. That, and the fact that a cursory Google search would likely explain everything. I suppose somebody felt that this fit the bill for "This question does not show any research effort". Personally, while I agree, I don't think you deserve a downvote since the mirror universe is such an important part of the Star Trek universe.
    – RivieraKid
    May 10, 2012 at 11:33

4 Answers 4


The mirror Universe is a parallel reality wherein Earth is far more militaristic than it is in the "prime" Universe, and wound up conquering its way to galactic prominence to form the Terran Empire. Memory Alpha has a whole article devoted to the details.

It was introduced in the original series' episode, "Mirror, Mirror" and became a prominent side-arc in Deep Space Nine. It was not featured at all in The Next Generation or Voyager, which is why you haven't run into it. It was, however, featured towards the end of Enterprise for a two-part episode.

If you're just interested in watching the mirror universe episodes, here's a chronological list (also from the above Memory Alpha article):

  • "In a Mirror, Darkly" from Enterprise (two parts)
  • "Mirror, Mirror" from the original series
  • "Crossover" from Deep Space Nine
  • "Through the Looking Glass" from Deep Space Nine
  • "Shattered" Mirror from Deep Space Nine
  • "Resurrection" from Deep Space Nine
  • "The Emperor's New Cloak" from Deep Space Nine
  • Ok that answers why I never saw anything about it, lol. Thanks! May 8, 2012 at 18:50
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    @OghmaOsiris Yeah, IIRC, the mirror universe from "Mirror, Mirror" was something the DS9 guys thought they could use to differentiate itself from the other series running at the time.
    – user366
    May 8, 2012 at 18:53
  • If I recall correctly, the Mirror Universe also appears in the computer game Star Trek Voyager Elite Force. Nov 1, 2013 at 3:51
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    While the literary canon is incredibly inconsistent, there is also "Dark Mirror" (en.memory-alpha.org/wiki/Dark_Mirror) which featured ST:TNG's mirror universe.
    – FuzzyBoots
    Mar 18, 2014 at 14:48
  • @FuzzyBoots There's also the comic miniseries "Mirror Broken", which features a goatee-wearing Picard and a Borg-enhanced Data. Also, Wesley gets ahold of the Agony Booth controls at one point. Jan 14, 2018 at 19:08

I assume you're referring to Star Trek's Mirror Universe. You managed to watch the two Star Treks that have no Mirror Universe episodes, which is kind of stunning. The Mirror Universe was introduced in The Original Series' (TOS) Mirror, Mirror, but you don't have to watch that episode to get a good introduction to that universe.

The Mirror Universe returned in Deep Space 9's Crossover, which is probably a more palatable introduction to the Mirror Universe if you don't like the 60's style/writing/etc of The Original Series. Just know that Kirk and friends made it over there first, they explicitly reference it in that episode to confirm that they're in the Mirror Universe. Over the course of DS9's run they return to the Mirror Universe periodically.

The last time we saw the Mirror Universe (out of universe chronology), was in an Enterprise (ENT) 2-parter. In a Mirror, Darkly was a 2 part episode that takes place entirely in the Mirror Universe. This arc was a bit more tied to The Original Series, so if you're not a TOS or ENT fan, just skip this.

In this alternate universe, things are more brutal. Familiar characters are more violent and the Federation as we know it doesn't exist. Instead, there is a Terran Empire in the 22nd-23rd century, which has its roots back on Earth, where history is more violent (the Enterprise episodes had an alternate opening along with dialogue that indicated this). Across the galaxy, there are other political differences. In the DS9 episodes, we learn that after the collapse of the Terran Empire, a Klingon-Cardassian Alliance rose to fill the power vacuum. They serve as the main antagonist in the DS9 Mirror Universe episodes.

Memory Alpha provides a handy list of Mirror Universe appearances:

  • Enterprise
    1. In a Mirror, Darkly (parts 1 and 2)
  • The Original Series
    1. Mirror, Mirror
  • Deep Space 9
    1. Crossover
    2. Through the Looking Glass
    3. Shattered Mirror
    4. Resurrection
    5. The Emperor's New Cloak
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    "In a Mirror, Darkly" is great to watch if only for the intro, especially if you disliked the hammy regular intro for Enterprise.
    – user366
    May 8, 2012 at 19:03
  • @MarkTrapp Yeah that was a pretty fun alternate intro.
    – user1027
    May 8, 2012 at 19:10
  • Good answer, though you seem easily stunned :) May 8, 2012 at 19:26
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    @MarkBeadles He hasn't seen DS9! The best of Treks!
    – user1027
    May 8, 2012 at 19:28
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    An opinion which I in turn find stunning. Touché. Well played, sir. May 8, 2012 at 19:29

You'd need to watch "Mirror Mirror" (as mentioned by Donald.McLean) from TOS and "Parallels" from TNG.

Here's a link to the wikipedia page for "Parallels." http://en.wikipedia.org/wiki/Parallels_(Star_Trek:_The_Next_Generation)

The 2009 movie is based on the concept of parallel realities, not necessarily universes, wherein minor changes in a timeline can produce entire new realities. See our discussion here. Do parallel realities take precedence over time travel in the Star Trek Universe?

  • My question actually wasn't a reference to that question lol. I just remember seeing references to a parrallell universe where the timeline is different. I think it has something to do with the Klingon empire, but I dunno. Does this answer still reflect this? May 8, 2012 at 18:47
  • I would think so, but I don't recall alternate universes in relation to any Klingon plotlines. The physics of the universe should be consistent across iterations of the show.
    – SocioMatt
    May 8, 2012 at 18:50
  • @OghmaOsiris The mirror universe does have a plot arc involving the Klingon Empire, but I wouldn't want to spoil it for you.
    – user366
    May 8, 2012 at 18:55

Plus, if it split off, Zephran would have been carrying a gun in the normal universe seconds before the split. It is possible that he considered attacking Geordi La Forge, but it shows no sign of that in the movie. My theory is the world split sometime in the 1950's, which would explain why the first moon landing has the Terran flag, not the American, and why the astronaut has an EV Suit. Theoretically,the first moon landing happened just a few years before first contact. The early split off would suggest that the Empire never encountered the Borg, so they never had to go back and stop them.

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