Doctor Who; Spock from
Star Trek; the Crystal Gems in
Steven Universe; Valkyrie, Gamora, and Nebula from the Marvel Cinematic Universe … our most beloved characters often come from other worlds, even if they’re recognizably played by human actors.
Alien characters don’t just entertain us with their strange and unfamiliar ways — they also reflect our humanity back to us. Science fiction is all about exploring what it means to be human, and we can do that more easily by comparing ourselves against the alien characters we love or hate. This works a couple of different ways for writers:
You can create alien characters who act human in many ways, except for a few major differences — and those differences can provide a contrast that reveals something about that human-seeming behavior.