Because you like Stifler's Mom in American Pie
Wanderer is a Soul, a parasite sent into a host to take over their body, extracting information from them and colonizing their species. See them in The Host.
Kara "Starbuck" Thrace will beat you in cards, drink you under the table, then fly circles around you in her fighter plane. See them in Battlestar Galactica.
Britta Perry has never met a cause she couldn't passionately champion—at least for a little bit. See them in Community.
Rose Tyler may have not done too well in school, but she's certainly holding her own in space. See them in Doctor Who.
Marv is a brutish but principled thug who'd be right at home on an ancient battlefield. See them in Sin City.
Daphne Blake's unfailing enthusiasm keeps the team's morale up even as they're battling evil spirits and other ghouls. See them in Scooby-Doo.
As high-strung as she is talented, Rachel Berry both marches and sings to the beat of her own drum. See them in Glee.
Winston Bishop is sweet, thoughtful, and a little oblivious. And above, he's a loyal friend. See them in New Girl.
The destroyer, Drax lives for one thing and one thing only: revenge. See them in Marvel Cinematic Universe.
Riley Blue is trying to outrun her bad luck, but she might not be fast enough. See them in Sense8.