Overweight, asthmatic, intelligent, annoying.
He's the kid you like not liking in school. There are a million little things about him that make him "different" from other kids, but really bugs people is when he thinks up a good idea or plan instead of the actual "leaders". Because of his appearance, he is a natural target for a classic bully like Jack. In addition, because just about everyone can easily pick on Piggy, he becomes the butt of any joke that can make everyone laugh and bring them closer together when things are on edge.
Piggy is bigger and smarter than all of the other boys and this makes him an outcast. No one really likes him, even Ralph makes fun of him in the beginning. He has asthma and wear glasses and talks a lot. He stays by Ralph's side, which causes him to be killed.