Arsinoe. I. A concubine of Philip, the son of Amyntas, who became the wife of Lagus, a Macedonian general, and the mother of Ptolemy I., king of Egypt. She was said to have been pregnant at the time of her marriage, and her son Ptolemy was generally regarded as the brother of Alexander.

II. A daughter of Ptolemy I., king of Egypt, was married to Lysimachus, king of Thrace, who had cast off his former wife Amastris that he might espouse her. Arsinoe, being determined to secure the Thracian sceptre for her own issue, caused her stepson Agathocles, the son of Macris, to be put to death. Lysandra, the widow of Agathocles, fled to Syria with her children, and implored Seleucus to avenge the murder of her husband. A war ensued between the Thracian and Syrian monarchs, in which Lysimachus lost his life (281 B. C). After this catastrophe Arsinoe sought refuge in Cassandria, a city of Macedonia, where, with her sons by Lysimachus, she remained in security for some time. But Ptolemy Ceraunus, having in 280 assassinated Seleucus and seized the crown of Macedonia, desired to gain Cassandria and get the heirs of Lysimachus into his power; he made an offer of his hand to Arsinoe, who accepted it. No sooner, however, did Ceraunus find himself in possession of the city than he caused the children of Lysimachus to be slain in the presence of their mother.

Arsinoe now fled from Cassandria to Samothrace, whence she proceeded to Egypt. Here she was kindly received by her brother Ptolemy Philadelphus, the king, who speedily made her his queen.

III. A daughter of Ptolemy Euergetes, wife of her brother Philopator, whom she accompanied to the war against Antiochus the Great in 217 B. C. Some years later a courtier named Phil-ammon put her to death by order of the king; but her murder was subsequently avenged by her friends, who killed Philammon and all his family. She was the mother of Ptolemy Epi-phanes by Philopator.

IV. A daughter of Ptolemy Auletes, was proclaimed queen by the Alexandrians after her brother Ptolemy Dionysius had become prisoner to Caesar (47 B. C. She subsequently, however, fell into the hands of the conqueror, was carried to Pome, and served to adorn his triumph (46). Her deportment excited the sympathy of the Roman people, and CAeesar permitted her to return to Egypt. In 41 Antony, at the instiga-tion of her sister Cleopatra, had her taken from the temple of Diana at Miletus, whither she had fled for refuge, and put to death.