Mirror Universe (Star Trek)

The Mirror Universe is a fictional parallel universe in which the plots of several Star Trek television episodes take place. It resembles the fictional universe in which the Star Trek TV series takes place, but is separate from the main universe. The characters in the Mirror Universe are aggressive, mistrustful, and opportunistic in personality. Whereas the Star Trek universe depicts an optimistic future in which the Earth-based United Federation of Planets values peace, co-operation and exploration, episodes set in the Mirror Universe feature the human-dominated authoritarian Terran Empire which values war, despotism, and conquest instead. The Mirror Universe has been visited in one episode of Star Trek: The Original Series, five episodes of Star Trek: Deep Space Nine and a two-part episode of Star Trek: Enterprise as well as several non-canon Star Trek novels and video games. It is named after "Mirror, Mirror", the original series episode in which it first appeared.

The Mirror Universe was first introduced in the original Star Trek episode "Mirror, Mirror", which featured the brutal Terran Empire, run by humans and their Vulcan allies, in place of the United Federation of Planets. The Mirror Captain Kirk of the ISS Enterprise was a mass murderer who was promoted to Captain after assassinating Captain Christopher Pike. Discipline aboard starships was enforced through torture — either through agonizers carried by crewmembers or agony booths. Officers were barbaric in behavior and advanced in rank by killing superiors who they thought were incompetent. Roman/Nazi-style military salutes were used by crewmembers to show loyalty to their captain.

The Mirror Universe was later revisited in the Deep Space Nine second-season episode "Crossover", and turned into a storyarc that spanned into the final season, with five Mirror Universe episodes over the course of five seasons. The show reveals that when exposed to individuals from the normal universe, the Terran Empire began to reform itself for the better, but was overthrown in the 23rd century by an alliance of alien species who took advantage of the Empire's self-weakening and conquered it, enslaving Terrans and Vulcans in the process.

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