Nelson Muntz is the bully on The Simpsons and is voiced by Nancy Cartwright.  Nelson is probably best known for his class "Hah Hah" laugh he does at everyone.

Though Nelson is typically foun bullying Bart and other students, we've also seen his softer side as Lisa's boyfriend and even as Bart's friend.

Nelson Muntz Quotes

Goon #2: Nelson, you're bleeding.
Nelson: Nah, happens all the time. Somebody else's blood splatters on me. (Sniffs) Hey, wait a minute. You're right. (to Bart) You made me bleed my own blood!

Nelson [about the school's ancient computer]: My stroked out grandfather has more memory tha that thing
Milhouse: How's he doing?
Nelson: Better, thanks

The Simpsons Quotes

Officer Eddie: (reading Steve Sax's license) Well well, Steve Sax, from New York City.
Officer Lou: I heard some guy got killed in New York City and they never solved the case. But you wouldn't know anything about that now, would you, Steve?
(Lou and Eddie laugh)
Steve Sax: But there are hundreds of unsolved murders in New York City.
Officer Lou: You don't know when to keep your mouth shut, do you, Saxxy Boy?

Wow, now I see why they call you Miss Hoover. You must have been vacuuming for an hour.

Bart