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.
I like to cry at the ocean, because only there do my tears seem small.</i> Nelson
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.