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.
[9] In Star Trek: Discovery, it is stated that humans from the Mirror Universe suffer from photophobia (a sensitivity to light).
[7] Spock's double wore a goatee, which became a popular culture trope as a visual marker for an evil version of a character.
[10][11] In 2018, Comic Book Resources rated Discovery's Mirror Universe saga as the 18th best multi-part episode story of Star Trek.
In addition to the television episodes, a number of ancillary tie-in works make use of the Mirror Universe setting.
[13][23] The Star Trek: Stargazer novel Three by Michael Jan Friedman features the Mirror Universe.
The point of divergence initially appears to be the Eugenics Wars where the genetic supermen were not defeated and eventually turned on each other resulting in atomic war, but works dating back to the days of ancient Greece supporting the Empire's current mindset are noted.
[1][better source needed] The concept of a morally inverted universe had been pioneered by DC Comics in 1964, three years before Star Trek adopted the idea, in the Justice League of America story "Crisis on Earth-Three" written by Gardner Fox.
[34][35] The fan-produced web series Star Trek Continues included an episode set in the Mirror Universe called "Fairest of Them All".