Because you like Brain in Pinky and the Brain
Roger is a pansexual alcoholic non-human who will happily lie, cheat and steal to get what he wants. See them in American Dad!.
After years of living vicariously through other people's heroic stories, Wade Watts is about to become a hero himself. See them in Ready Player One.
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.
Dorothy Gale is a down-home Kansas girl in a bizarre fantasy land with beautiful red shoes. See them in The Wizard of Oz.
Vincent Vega likes a good steak, a cheap milkshake, and killing a target without anything going wrong. See them in Pulp Fiction.
As a doctor-in-training, John Dorian should have his head in the game. But most of the time, it's in the clouds. See them in Scrubs.
Cyclops shoots lasers out of his eyes, destroying anything in his line of sight. See them in X-Men Series.
Khan Noonien Singh is super strong, super smart, and out for revenge. He always seems to be two steps ahead of his enemies. See them in Star Trek Into Darkness.
Gene Belcher dreams of a future in the limelight, and he doesn't let his lack of talent hold him back. See them in Bob's Burgers.
Donkey is proof that if you're annoying enough you can change the world; he's the reason that his friend Shrek does, well, anything. See them in Shrek.