Jack, on the other hand, shows us that all men, even antagonists, can be good guys from time to time. Jack’s “inexplicable connection” to Ralph makes us think twice about drawing a clear line between them. Both boys are leaders, both are strong (physically and in character), and both are looked up to by the other boys. But Jack’s lust for power, blood, violence, cruelty, and eventually his lust for Ralph’s death, qualifies him quite well as an antagonist.
The beast can also be considered an antagonist. In the literal sense, you could say the beast is actually just the dead man in the parachute. Since he’s the product of war, the beast = war, and war is the antagonist. Or you could say, as Piggy does, that the beast is everyone’s fear, in which case, fear = the antagonist, which we could happily believe. Lastly, you could jump in Simon’s boat and say that the beast = “only us,” i.e., the darker side of human nature. This, you could say, exonerates Jack from being the antagonist, since it’s not his fault he’s human and has this darker streak. You could also say that calling “the beast” the antagonist reinforces Jack as being the enemy, since the beast equals people – people like Jack.