It all began with a goatee-wearing Spock (Leonard Nimoy) in the Star Trek Mirror Universe. The concept of the Mirror Universe within Star Trek premiered in 1967, and it didn't just introduce parallel worlds to sci-fi television—it essentially invented the visual language of the evil counterpart. The iconic Mirror Universe will forever be known as the multiverse genre's godfather, but that concept has only shown up as a recurring guest star across different eras and shows—rarely as the main character.