Because you like Grunkle Stan in Gravity Falls
Louise Belcher might be just a kid, but she can manipulate just about anyone with a pulse. All in the name of fun, of course. See them in Bob's Burgers.
Garnet is a Crystal Gem who'll protect her friends with her life. See them in Steven Universe.
Experiment 626 was designed for one thing: to destroy everything he touches. See them in Lilo & Stich.
Squidward Tentacles is a pretentious clarinet player in search of peace and quiet. See them in SpongeBob SquarePants.
Buddy Pine is an unhinged superfan of superheroes using technology to take down his idols. See them in The Incredibles.
Bob Parr is an ex-superhero now focused on being a dad, but he misses the action. See them in The Incredibles.
Philip J. Fry accidentally cryogenically froze himself for a millennium. See them in Futurama.
Once a handsome prince, the Beast is now a grumpy, furry, monster. It's hard to pinpoint which mammal he resembles the most. See them in Beauty and the Beast.
Driven and straightforward with high-technology parts, EVE was sent to Earth to see if it is habitable. See them in WALL-E.
The Grinch's heart is just too small to appreciate Christmas. See them in Dr. Seuss' How the Grinch Stole Christmas.