4) Mirror, Mirror
Star Trek’s first foray into the evils of the Mirror Universe alt-reality is still arguably its finest, over a half-century later. But what makes it work is not necessarily just the sinister, moral-inversion idea of an Enterprise and Federation (now rendered the Terran Empire) that works for horrifying goals rather than idealistic ones. It’s also Kirk’s inherent struggle and horror at trying to temporarily survive in that world—not because he doesn’t think he’s capable of effectively sneaking about as his Mirror self when he’s transported to the alternate reality, but because of disgust at having to hide the good man he really is.
