(Κασσάνδρα), also called Alexandra (Paus. 3.19.5, 26.3), was the fairest among the daughters of Priam and Hecabe. There are two points in her story which have furnished the ancient poets with ample materials to dilate upon. The first is her prophetic power, concerning which we have the following traditions : Cassandra and Hellenus, when yet children, were left by their parents in the sanctuary of the Thymbraean Apollo. The next morning they were found entwined by serpents, which were occupied with purifying the children's ears, so as to render them capable of understanding the divine sounds of nature and the voices of birds, and of thereby learning the future. (Tzetz. Argunm. ad Lycoph.; Eustath. ad Hom. p. 663.) After Cassandra had grown up, she once again spent a night in the temple of the god. He attempted to surprise her, but as she resisted him, he punished her by causing her prophecies, though true, to be disbelieved by men. (Hyg. Fab. 93.) According to another version, Apollo initiated her in the art of prophecy on condition of her yielding to his desires. The maiden promised to comply withhis wishes, but did not keep her word, and the god then ordained that no one should believe her prophecies. (Aeschyl. Agam. 1207; Apollod. 3.12.5; Serv. ad Aen. 2.247.) This misfortune is the cause of the tragic part which Cassandra acts during the Trojan war : she continually announces the calamities which are coming, without any one giving heed to what she says; and even Priam himself looks upon her as a mad woman, and has her shut up and guarded. (Tzetz. 1. c. ; Lycoph. 350; Serv. ad Aen. 2.246.) It should, however, be remarked, that Homer knows nothing of the confinement of Cassandra, and in the she appears perfectly free. (Il. 24.700; comp. Od. 11.421, &c.) During the war Othryoneus of Cabesus sued for her hand, but was slain by Idomeneus (Il. 13.363); afterwards Coroebus did the same, but he was killed in the taking of Troy. (Paus. 10.27.1; Verg. A. 2.344, 425.)

The second point in her history is her fate at and after the taking of Troy. She fled into the sanctuary of Athena, and embraced the statue of the goddess as a suppliant. But Ajax, the son of Oileus, tore her away from the temple, and according to some accounts, even ravished her in the sanctuary. (Strab. vi. p.264; comp. AJAX.) When the Greeks divided the booty of Troy, Cassandra was given to Agamemnon, who took her with him to Mycenae. Here she was killed by Clytaemnestra, and Aegisthus put to death her children by Agamemnon, Teledamus, and Pelops. (Aeschyl. Agsam. 1260; Paus. 2.16.5; Hom. Il. 13.365, 24.699; Od. 11.420.) She had a statue at Amyclae, and a temple with a statue at Leuctra in Laconia. (Paus. 3.19.5, 26.3.) Her tomb was either at Amyclae or Mycenae (2.16.5), for the two towns disputed the possession of it.

There is another mythical heroine Cassandra, who was a daughter of Iobates, king of Lycia. (Schol. ad Hom. Il. 6.155; comp. BELLEROPHON.)