Because you like Martha Jones in Doctor Who

Did he ever tell you the definition of insanity? Just wait, and this psychopath will do just that. See them in Far Cry 3.

Pro: Johan Liebert is handsome and charming. Con: he's also a sociopathic killer. See them in Monster (TV Show).

Teddy Sanders loves his frat brothers so much he might never leave school. See them in Neighbors.

Carl Gallagher is a budding psychopath fascinated with rule breaking. See them in Shameless.

Misato Katsuragi is never without a beer in her hand or her pet penguin by her side. See them in Neon Genesis Evangelion.

Not a great influence with her classmates, this 13-year-old "cool girl" likes to shoplift, chug alcohol, and snort crushed pills. See them in thirteen.

Manipulative, gorgeous, and sharp as a tack, Blair Waldorf is a classic product of the Upper East Side. See them in Gossip Girl.

Steve Stifler is more than just a dude with a hot mom. He's also rude, profane, and obnoxious. See them in American Pie.

Convinced that the world is conspiring against him, Tatsuhiro's reconciled himself to his fate as a shut-in. See them in Welcome to the NHK.

After becoming accepted into the group of popular girls, Tracy Freeland has turned from a sweet and reserved teenager into a monster. See them in thirteen.