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

Bart: Boys and girls, Mrs. Krabappel, I come before you today to solve a riddle that has plagued mankind for centuries: What has four legs and ticks?
Milhouse: A walking clock?
Nelson: A walking clock!
Martin: I'd wager he has some variety of walking clock in that box!
Edna: Bart, is it a walking clock?
Bart: What?.....No, it's my dog.

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

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!

Horst: (Sinister) Okay, Mr. Burns, you win. But beware. We Germans aren't all smiles and sunshine.
Mr. Burns: (Sarcastic) Oooh, the Germans are mad at me. I'm so scared! Oooh, the Germans! (Hiding behind Smithers) Uh oh, the Germans are going to get me!
Horst: Stop it!
Man: Stop, sir.
Mr. Burns: Don't let the Germans come after me. Oh no, the Germans are coming after me.
Man: Please stop the "pretending you are scared" game, please.
Horst: Stop it! Stop it!
Mr. Burns: (Pause) No! They're so big and strong!
Man: Stop it.
Horst: Stop it, Mr. Burns.
Man: Please stop pretending you are scared of us, please, now.
Mr. Burns: Oh, protect me from the Germans! The Germans--
Horst: Burns, Stop it!