Because you like Will Hunting in Good Will Hunting
Seth is short-tempered, crude, and terrible at school, but hopefully there's nothing an epic party can't fix. See them in Superbad.
Sephiroth wants nothing more than to seize the power of the Lifestream in order to become a god. See them in Final Fantasy Series.
A malevolent dark wizard, Voldemort is so fearsome that he's known primarily as "He Who Must Not Be Named." See them in Harry Potter Series.
Maya Lambert is an obsessive intelligence officer with tunnel vision leading toward Osama bin Laden. See them in Zero Dark Thirty.
Randy Marsh is a geologist and Nobel Prize winner who is into binge drinking, starting riots, the Food Network, and P.F. Changs. See them in South Park.
Nadine Franklin likes to wallow in her misery almost as much as she likes to torment her mother. See them in The Edge of Seventeen.
While he might drive colleagues crazy with his antics, Jake Peralta cares about the Nine-Nine more than most things. Including personal hygiene. See them in Brooklyn Nine-Nine.
Gregor Samsa is an ordinary man in an abnormal predicament. See them in The Metamorphosis.
A short-tempered guy, Bowser is determined to wreak havoc on the Mushroom Kingdom. See them in Super Mario Bros..
Simon Belmont is a vampire hunter bravely carrying on the family business. See them in Castlevania.