Laocoon was a Trojan priest of Poseidon at the time of the Trojan War. As the Trojans are debating as to what to do with the huge horse the Greeks have left behind, Laocoon speaks up. He says that there are either men in the horse, or that it is a huge siege engine. He then utters the famous phrase, 'I fear the Greeks, even when bearing gifts.' At the end of the speech, for dramatic purposes he hurls a spear into the side of the horse.
After the words of Sinon, Laocoon was preparing a sacrifice to Poseidon. Suddenly, two snakes attacked and devoured Laocoon and his sons. This was because Laocoon had married against Poseidon's will. The Trojans, however, did not know this. They assumed this to be a sign from the gods, and brought the horse within their walls.