History MirrorUniverse / StarTrek

** The third season of ''Discovery'' reveals that the Starfleet of the fourth millennium has figured out how to scan for the specific genetic differences between humans and Terrans in order to catch any "visitors" from the other universe. Furthermore, they claim to have isolated a protein chain that supposedly makes Terrans evil. Georgiou brushes off their claims as overly simplistic. It's also revealed that the two universes have moved apart, and there haven't been any visitors in 500 years.

* The Ultimate Universe mod for ''VideoGame/StarTrekLegacy'' includes a bunch of Terran Empire equivalents of Federation ships from the ENT, TOS and TNG eras

** The emperor is eventually identified as [[spoiler:Wesley Crusher]], though they relinquish the position after the Terran Gambit arc, replaced by [[spoiler:Leeta]] with [[spoiler:Marshal Janeway and her borg armies]] at their side.

* In ''VideoGame/StarTrekOnline'', your character doesn't get an Evil Counterpart via MirrorUniverse, but the ''ships'' do. And these ships are also playable via lockbox drops.

* As part of the Terran Gambit arc, the player does finally get to see, play as, and eventually meet their own Mirror Universe counterpart, known as [[https://stowiki.net/wiki/Player_character_(mirror) The Inquisitor]]. They have the player character's build and face, but they wear a Terran uniform and have an artificial voice box on their throat. Earlier missions had a character state that she had killed the player's mirror counterpart, but these new missions retcon it into her merely ''trying'' to kill them and falling (instead ruining their vocal chords, requiring the voice box). The devs say she was lying (which is entirely in-character for her).

[[folder:Fan Works]]
* {{Downplayed}} in ''Fanfic/TheWrongReflection'', a ''VideoGame/StarTrekOnline'' fanfic dealing with the TropeNamer. The makeup of the prime universe Captain Kanril Eleya's crew means there physically ''can't'' be a straight-played evil version of the USS ''Bajor'': In ''Series/StarTrekDeepSpaceNine'' Bajor is part of the Klingon-Cardassian Alliance in the mirror universe--the Occupation of Bajor was perpetrated by ''humanity'' and they were freed by the Alliance conquest--but most of the members of Eleya's senior staff are Terran species. So instead other things get changed: Mirror Kanril is the XO on a Cardassian battleship and a darker version of the AntiHero compared to the PragmaticHero Eleya.
[[/folder]]

** When the prequel series ''[[Series/StarTrekEnterprise Enterprise]]'' revisited it in "In A Mirror Darkly," it also completely [[SpecialEditionTitle changed its opening credits']] entire mood from "Idealistic Yet Not Naive Hope" to "War! Conquest! ''Exploding [[SlowLaser Slow Lasers]]!''" Moreover, since almost everyone except maybe the Vulcans is shown to be evil in one way or another, the ending in which TheBadGuyWins doesn't really come as a surprise. What ''does'' come as something of a twist is [[spoiler: it's the bad ''gal'' who wins, and then promptly proclaims herself Empress.]]
** Certain other aspects of characters are flipped in the mirror universe as well. In ''Series/StarTrekDeepSpaceNine'', Bashir is a [[DumbMuscle stupid and brutish thug]] (most likely due to never having been genetically altered), Odo is a [[TheBully sadistic slave overseer]], Jadzia is a PsychoKnifeNut who is mirror Sisko's lover, mirror Sisko (while a good guy) has very little in the way of restrained self-control, and mirror Ezri and Leeta (while also not villains, though also not squeaky-clean) are both lesbians. ''[[CorruptCorporateExecutive Brunt]]'' of all people becomes a NiceGuy. Things get ridiculous when an [[SerialEscalation entirely fictional holodeck character appears as a real person]], (perhaps his mirror creator makes androids instead of holodeck characters?) whereupon everyone gives up trying to make sense of things.

** Also, the ExpandedUniverse ''does'' show us more than one version of the Mirror Universe, though whether it's intentional or simply the Trek EU not being having nearly as tight continuity as the ''Franchise/StarWars'' one is unknown. "Dark Passions" is quite incompatible with the Shatnerverse version, for example. Also, one book written ''well'' after ''[[Series/StarTrekDeepSpaceNine [=DS9=]]]'' features several alternate universes, including one featuring the ISS ''Enterprise''-E of the Terran Empire, which doesn't work with the [=DS9=] incarnation of the MU, so that one is clearly deliberately alternate from the beginning.
** It also explores how long the unique mindset of the Terran Empire has been around. In ''Dark Mirror'', Picard reads that universe's version of ''Theatre/TheMerchantOfVenice'', which has Portia saying "The quality of mercy must be '''''earned'''''", and pointing how it's silly to expect a pound of flesh not to have blood too, allowing Shylock to get his revenge. Picard sees Literature/TheBible and refuses to read it.
*** It should be noted that the show does occasionally show us parallel universes that are not the 'Mirror Universe.' In the ''Series/StarTrekTheNextGeneration'' episode "Parallels", Worf is stuck traveling between different realities in which there are mostly only minor differences. The only semi-villainous alternate main character was a Riker from a timeline in which the Borg had assimilated much of the galaxy, who fired on Worf's shuttle, desperate to avoid returning to his native universe. He does sport a much more wild and unkempt beard than our Riker, but it is clearly a BeardOfSorrow rather than a BeardOfEvil.
*** The episode "Parallels" does show one Mirror Universe from the Bajorans perspective, as in one is them who are the enemies of the Federation (not the Cardassians) and who actually conquest Cardassia and not the other way around.

*** There were several non-canonical sources made between before [=DS9=] that explored the Mirror Universe. As the setting wasn't as well defined as it was later by [=DS9=] some continuity elements may shock some readers. For example the term "Terran" wasn't coined until [=DS9=], thus the works refer to the Empire (which was nameless in the original "Mirror, Mirror" episode) as the United Empire of Planets (for example in the TNG novel ''Dark Universe'', in which the Empire is still pretty much fine in the 24th century) and in some countinuities as the Human-Vulcan Empire with Vulcans, Andorians and Tellarites having more equal footing in the Empire than was shown in ''Enterprise''. However this might explained why Vulcans shared the punishment and were turn into slaves by the Klingon-Cardassian Alliance.
** [[Recap/StarTrekVoyagerS4E21LivingWitness "Living Witness"]] opened with what appeared to be a mirror universe setting, with a vicious Janeway threatening a planet to get resources. [[spoiler: It turned out to be an inaccurate historical record written by this civilization some time in the future, based on an incident with Voyager several hundred years ago. The holographic doctor's backup unit is later activated and sets the record straight.]] Those familiar with Deep Space 9's episodes likely knew it wasn't the case, those who hadn't been watching...

** The video game ''VideoGame/StarTrekOnline'' revisited the Mirror Universe. Unlike other Expanded Universe entries, this Terran Empire went right back to being tyrants after liberating themselves from the Klingon Alliance. Prior to the Season 11 update, the emperor was James O'Brien, son of "Smiley" O'Brien, who attempted to alter the Bajoran Wormhole to initiate a full-scale invasion of the Prime universe. Season 11 changed this so that the empire was now ruled by an unidentified emperor with strange powers, with the main threat on the Prime side being the mirror universe Leeta, who as an admiral fought and won their own Iconian War via weaponry from the future and now seeks to invade our world as a staging ground for a bid to the throne.
** ''[[Series/StarTrekDiscovery Discovery]]'' revisits the Mirror Universe, when the spore drive malfunctions and sends the ship there. The crew manage to get their hands on a rebel database, allowing them to brush up on this world's history. They realize that their only way back is to find the USS ''Defiant'' that ended up there in ENT. We're also shown a glimpse of Captain Sylvia Tilly of that universe, who is as bloodthirsty and vicious as the original Mirror!Kirk. Burnham's double is, apparently, not much better. On the other hand, the double of the morally-ambiguous Lorca is a good guy, who attempted to rise up against the Emperor. [[spoiler:Until we found out Lorca that we know is actually the same mirror universe Lorca, and the entire happenings during the first half of season 1 is orchestrated by him]]
*** We are also introduced to the one biological difference between a Mirror Universe Terran and Prime Universe human: [[spoiler:[[WeakenedByTheLight sensitivity to light]]. This is how Michael recognizes that the Lorca she serves under is actually from the Mirror Universe. And it retroactively explains why Mirror Universe ships had poorer lighting]].
*** We also meet the reigning emperor of the Terran Empire - [[spoiler:Phillipa Georgiou, who is as different from Captain Phillipa Georgiou as day from night. When she ends up in the Prime universe, courtesy of Burnham, the first thing she does is nearly shoot Commander Saru for not immediately bowing down to her, as befits a proper slave (he's an alien, therefore a slave in her universe). She then convinces Starfleet to allow her to destroy Qo'noS, just like she did in the Mirror Universe, in order to force an end to the war]].
*** This arc does explore some implications that are ignored in the other shows. Given that the Mirror counterparts are bloodthirsty and evil, [[ChronicBackstabbingDisorder killing each other any chance they get]], and crossovers have been happening for centuries, it starts to stretch credibility that nearly everyone has a living counterpart as well as a somewhat similar background (Kirk is still captain of the ''Enterprise'', O'Brien is still an engineer at Deep Space Nine, etc). Michael discusses with several individuals the oddity of how similar yet different their background remained, and [[InSpiteOfANail implied some sort of cosmic element keeping the two universes connected]].
*** The third season of ''Discovery'' reveals that the Starfleet of the fourth millennium has figured out how to scan for the specific genetic differences between humans and Terrans in order to catch any "visitors" from the other universe. Furthermore, they claim to have isolated a protein chain that supposedly makes Terrans evil. Georgiou brushes off their claims as overly simplistic. It's also revealed that the two universes have moved apart, and there haven't been any visitors in 500 years.
** Season 2 of ''Series/StarTrekPicard'' introduces a ''different'' Mirror Universe, which is [[spoiler: actually the regular timeline, altered by Q changing the past]]. In this one, the dominant power is the Confederation of Earth rather than the Terran Empire, but it has much the same policies, only it seems to be more efficient because it's a more Lawful and less Chaotic evil. Picard is a ruthless general who collects the skulls of his enemies, Rios is a colonel fighting against the Vulcans, Seven is the President, with Agnes as her chief scientist and Raffi as her head of security, and Elnor is a Romulan freedom fighter. If anything, this is more chilling than the regular Mirror Universe, because while it's usually presented as [[NeverWasThisUniverse having always been like that]], this universe is specifically the result of something that happened as recently as [[NextSundayAD 2024]]. The Confederation of Earth is in many ways similar to the MirrorUniverse's Terran Empire. Both are xenophobic to the extreme, but the Empire focuses on enslavement, while the Confederation prefers to exterminate aliens. There also seems to be a lot less backstabbing in the Confederation, with loyalty to humanity being paramount. An interesting difference is that the Confederation Star Corps seems to use army ranks instead of navy ranks, so we have General Picard and Colonel Rios. This version of Picard is a ruthless conqueror, slayer of many aliens, including General Martok, Gul Dukat, and Sarek. Also, while the Empire was always on the verge of rebellion from the aliens, the Confederation seems to be a lot more successful in stamping out dissent and is even more successful militarily, having managed to defeat the Borg.
** ''WesternAnimation/StarTrekLowerDecks'' shows Mariner going into a holo-deck simulation of the MirrorUniverse which she calls it by that name. The simulation however shows the Terran Empire which by that time was already defeated.

* ''Franchise/StarTrek'' makes several visits to or in some way involves the Mirror Universe.
** The ''Series/StarTrekTheNextGeneration'' [[Franchise/StarTrekExpandedUniverse novel]] "Dark Mirror" explores a Mirror Universe where the Terran Empire, or the United Empire of Planets as its called here, survives well into the 24th century after Spock's efforts to reform the Empire fail. By the 2360s the Empire is running out of space to conquer and [[spoiler:makes an unsuccessful attempt to conquer the prime universe.]] [[note]]Obviously, the novel was written several years before ''Series/StarTrekDeepSpaceNine'' explains what [[Recap/StarTrekDeepSpaceNineS02E23Crossover really happened]] to the Empire after Kirk left. However since the episode "[[Recap/StarTrekTheNextGenerationS7E10Parallels Parallels]]" established that an infinite number of parellel universes existed this could provide an explanation of why the "Dark Mirror" Mirror Universe was different.[[/note]]
** ''Literature/StarTrekShatnerverse'' novels explain that the Klingon-Cardassian alliance was the brainchild of former Emperor Kirk as a means of taking revenge on Spock for deposing him from the throne and to regain the Terran Empire's throne for himself. This was mainly due to Mirror Spock deciding not to kill Kirk after his return.[[spoiler: Spock did manage to save the Halkans by claiming they were a client state of the Klingons and that attacking them could lead to a war with the Klingons that the Empire didn't want at the time. This resulted in Kirk getting a commendation for seeing through the Halkan trap.]]
** In the ''Literature/StarTrekNovelVerse'' novels set in the Mirror Universe established that Spock was unable to convince Kirk to spare the Halkans and got in a fight with the man. Spock killed Kirk and then disposed of Kirk's body with the Tantalus Field. After Spock's opponents accquired the same habit of disappearing that Kirk's opponents used to have, dissent died down on the ISS ''Enterprise''. Gathering power and influence, Spock rose to command the Empire, which he soon disestablished in favor of the Terran Republic, but the Klingons and Cardassians still wanted revenge for the Empire's acts. Spock died on Earth in the novel verse, but his followers were able to engineer a rebellion that would in time liberate Earth and its allies from the Klingons and Cardassians.

** The [[Literature/StarTrekMirrorUniverse Star Trek novels]] continue the Mirror Universe after season seven of ''Deep Space Nine'', showing us how the Terran Rebellion is becoming more of a social revolution, as well as giving us perspectives on Mirror Spock's rise to power as Emperor after the initial episode "Mirror, Mirror", Empress Sato's putting down of the rebellion during the ''Enterprise'' era, and how Picard stopped being a slave and became a Terran Rebellion leader during the TNG era. [[spoiler: The MU gets a happy ending: As the mirror ''[[Series/StarTrekDeepSpaceNine [=DS9=]]]'' gang kicked much booty with their version of the Defiant, somebody got their hands on the ''Enterprise''-E's specs. The tide of the war is turned, this time by ''genuinely'' good guys and not an equally-brutal faction that the existing bad guys were keeping down. And now, the rebellion is victorious, and with the war over, they've got this nice shiny awesome spaceship that's no longer needed for battle. The ''Enterprise'' will now be used for exploration under the command of a rebel named Picard.]]

*** The IDW comic story "Mirrored" gives us the Mirror Universe of the [[Film/StarTrek2009 Kelvin Timeline]] Universe. As Captain Spock vanquishes the Klingons in the name of the Terran Empire, Commander Kirk vists Rura Penthe to get revenge on Nero (who in this universe never escaped, and has been there since the attack on the ''Kelvin''). Then Kirk ends up with control of the ''Narada'', and things get worse.