Cassandra was the most beautiful of the daughters of Priam and Hecuba, the king and queen of Troy . She was given the gift of prophecy by Apollo, who wished to seduce her; when she accepted his gift but refused his sexual advances, he deprived her prophecies of the power to persuade.

At the end of the Trojan War, Cassandra foresaw the danger posed by the Trojan horse; the people of Troy ignored her warnings and the Greek soldiers hiding inside the horse were able to capture the city. During the sack of Troy , Cassandra was raped by the Locrian (or "lesser") Ajax , and was then given as a war prize to Agamemnon. She returned to Greece with Agamemnon, and tried to warn him of the danger which awaited him there; once again her prophecy was ignored, and both she and Agamemnon were murdered by Clytemnestra and Aegisthus.