Agis (ā´jĬs), name of four Spartan kings. Agis I, fl. late 10th cent. BC, was the traditional founder of the Agiad dynasty, one of the two ruling dynasties of Sparta, which had a dual kingship. The other dynasty, the Eurypontids, fathered the succeeding Agises. Agis II, d. 398? BC, acceded to the throne on the death (c.427) of his father, Archidamus II. Agis led Spartan forces at the battle of Mantinea (418 BC) during the Peloponnesian War. Advised by Alcibiades, who had fled to Sparta to avoid trial at home, he quickly invaded Attica and established a post there. Later he quarreled with his adviser. Agis aided Lysander in the final Spartan victories of the war. Agis III, d. 331 BC, succeeded his father Archidamus III in 338. He led a revolt of Peloponnesian cities against Alexander the Great, who was in Asia. The rebels were crushed, and Agis was killed at Megalopolis. His death ended Greek revolts against Alexander. Agis IV, d. c.240 BC, son of Eudamidas II, succeeded his father c.244 BC He tried to revitalize Sparta by reform and by returning to the constitution of Lycurgus. His efforts failed, and he was murdered.