In Greek legend, a seer and priest of Apollo .
He was the son of Agenor of Troy or the brother of Aeneas 's father Anchises. Laocoön offended Apollo by breaking his priestly vow of celibacy and begetting children, and by warning the Trojans not to accept the wooden horse presented by the Greeks. While preparing to offer a sacrifice to Poseidon , he and his two sons were crushed to death by sea serpents sent by Apollo.