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

I like to cry at the ocean, because only there do my tears seem small.

</i> Nelson

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!

The Simpsons Quotes

(Bart shows the whole classroom the tape for his project called, "How Kittens Are Born: The Ugly Truth")
Bart: and here comes Snowball II. This is the one we kept.
All: EWW!!
Bart: We were gonna keep the gray one, but the mother ate her.
All: EWWWWW!!
Martin: Mrs. Krabappel, he's traumatizing the children!
Mrs. Krabappel: As usual, I agree with you, Martin. Bart, shut that off and take your seat immediately!
Bart: Oh, look! This is really cool. When I hit reverse, I can make 'em go back in.
(The whole classroom screams)

Homer: (Wearing glasses) The sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side!
Man: (From inside a bathroom stall.) That's a right triangle, you idiot!
Homer: D'oh!