Ralph: He is portrayed as the example of a British boy and to Golding's mind, he doesn't have bad character traits. First he recognises and treats Piggy as an outsider, but soon he finds out about his intelligence and his foresight. He is a very good leader because he rules not like a dictator and believes in his ideology and democracy.
Piggy: He has a unremarkable appearance, seems as a whining and overweight hypochondriac with glasses - the "born" outsider. He fears people, possibly because of his experiences. He is the most intelligent boy on the island, is good in organising things and has moral and physical courage.
Jack: Jack is a character Golding has intended you dislike and to get in conflict with the ideals he created in some of his other characters. He is arrogant, aggressive and greedy for leadership - but he has no qualities for being a chief, except the fact he wants it. His goal isn't to be rescued but to have a good time, go hunting, eat meat (which isn't essential for their surviving because of the big amount of fruit trees) - a consequence of this is his tendency to hunt people too.
He represents the Primitive man, the Hunter.
Another mistake of him is that he has no foresight. For example they kill a sow, which provides meat in the future and he destroys the fruit trees with the fire in the end while hunting Ralph. If they hadn't been rescued, they would have starved.
Simon: Golding describes him as one of the in-between boys. Simon has experiences with the older and the younger boys. He has the innocence and the feelings of the littluns but the knowledge of the biguns. However, Simon is also a kind of outsider. He takes life very serious and actually, he is the only one, who realises that the beast is not something one can kill because it's inside the boys. Simon is often regarded as a prophet, saint or Christ figure, because he died to tell the rest of the boys about the beast.
Sam & Eric: They behave like one person, for example they finish each other's sentences in the dialogues and are called Samneric. Maybe they aren't influenced by Jack's tribe, because together, they are strong enough to resist him.
The Naval Officer: He has a rather romantic view of how the life was like on the island. In the End he appears like a knight in shining armour.