first Mamlūk sultan of Egypt (1250–57) in the Turkish, or Baḥrī, line.

Upon the death of aṣ-Ṣaliḥ, the last great sultan of the Ayyūbid dynasty, his son succeeded him but offended his father's slave guards, or Mamlūks, who killed him (April 30, 1250). Shajar ad-Durr, aṣ-Ṣaliḥ's widow, thereupon proclaimed herself “queen of the Muslims”; she was recognized in Egypt, but the Syrian emirs refused to pay her homage. The caliph took the side of the Syrians and asked the Egyptian emirs to choose a man in her place. To elude this command the emirs of Egypt appointed Aybak as commander in chief, and he at once married Shajar ad-Durr. To placate the Syrian Ayyūbids, who were still dangerous, the emirs elected Musa, one of the Syrian branch of the family, as cosultan, and his name appeared on documents and coins. Aybak, however, was the effective ruler. His administration revealed a certain rough vigour, but he lacked the higher qualifications for leadership in the circumstances of Mamlūk Egypt. He antagonized the emirs; on Sept. 18, 1254, he killed a commander who had successfully suppressed an Arab rebellion in middle Egypt. Many Mamlūks, among them the future sultan Baybars I, fled to Syria out of the tyrant's way. Aybak met his death in a palace intrigue when his consort Shajar ad-Durr in a fit of jealousy had him murdered, whereupon, a few days later, the slave women of Aybak's first wife battered her to death. Aybak was succeeded as sultan by his son ʿAlī.