What does the creature represent in Lord of the Flies?

As the boys first gather on the island, no one mentions the beast and the boys seem excited at the prospect of being on their own and working to get rescued or hunting for meat. 

After their first meeting, however, the boy with the mulberry colored birthmark mentions the "beastie" that he saw in his sleep and the fear takes hold inside the boys. It appears that this beastie could represent their fear of the...

As the boys first gather on the island, no one mentions the beast and the boys seem excited at the prospect of being on their own and working to get rescued or hunting for meat. 

After their first meeting, however, the boy with the mulberry colored birthmark mentions the "beastie" that he saw in his sleep and the fear takes hold inside the boys. It appears that this beastie could represent their fear of the unknown, the fear of what might be on the island that they don't know about yet.

But as time goes on, it becomes clearer and clearer that the "beastie" represents something inside of them. As the conflict between Ralph and Jack and their "tribes" grows, Simon begins to understand that the beastie represents the darkness inside of themselves, the possibility of violence and savagery that exists inside them. The beast, represented by the pig's head in his visions, mocks Simon and the possibility that they could have "killed the beast."

The representation is solidified when Simon tries to share this knowledge with the boys and they allow their fear to overrule any reason and they kill him when he stumbles out of the woods.