The Terran Empire was a faction in the alternate "mirror universe" of the Star Trek franchise. Envisioned as the polar opposite of the Federation, it is portrayed as an expansionist regime, relying on military might and brutal oppression to maintain itself in a violent universe.
It is unclear when and how the Empire rose to prominence in the Mirror Universe. An Imperial flag is shown flying at the time of the Moon landing, suggesting the Empire was already a political entity in the alternate 20th century.
Throughout the 22nd and 23rd century, the Empire struggled to contain a rebellion of disgruntled citizens. While this rebellion came close to crippling the Imperial armed forces in the 2150's, it had been reduced to a nuisance in later years.
The Empire met its end following a series of reforms instituted by the alternate Spock, who aimed to scale back the Empire's aggression. These reforms left the Empire open to a coordinated attack by the Klingon-Cardassian Alliance, which absorbed the former Empire's territories and citizenry.
Little is known of the Empire's structure or society. It is portrayed as a form of meritocracy based on influence and guile; assassination is considered a valid method of ascension in rank, and personal loyalty to an officer can be rewarded with promotion. While women and non-humans are able to serve in the Imperial Starfleet, they are generally considered second-class citizens.
The only known Emperor is Hoshi Sato, who forcibly took the title in 2154.
The Terran Empire and its universe are well known and popular parts of the Star Trek franchise. "Mirror, Mirror" is among the most famous and popular TOS episodes in the library and was notable for spawning the cliché of a "goateed evil twin". The fan reaction to the fact that the Terran Empire had fallen by the DS9 era was very negative. The most popular episode of Star Trek: Enterprise was the "Mirror Universe" two-parter.
Episodes featuring the Terran Empire
- "Mirror, Mirror"
- "In a Mirror, Darkly" (parts 1 & 2)