Star Trek: Enterprise
The Mirror Universe first appeared in the original series as an alternate reality where the militaristic Terran Empire exists in place of the regular universe's United Federation of Planets (""). A montage in the opening credits of the "Star Trek: Enterprise" episode "In a Mirror, Darkly" shows the Terran Empire logo in use by at least World War II, with licensed novels putting the divergence before Shakespeare, or even classic Greek literature.