[s5e5] Mirror, Mirror -

"Mirror, Mirror" is the fourth episode of the second season of Star Trek: The Original Series that introduces the "Mirror Universe," a parallel reality where the Federation is replaced by a brutal Terran Empire. The episode, featuring a transporter malfunction that sends Captain Kirk and his crew into this dark reality, popularised the "evil twin with a goatee" trope. Watch a video explanation of the episode's legacy at YouTube . Star Trek – Mirror, Mirror