Ares (ârˈēz) [key], in Greek religion and mythology, Olympian god of war. He is usually said to be the son of Zeus and Hera; but in some legends he and Eris, his twin sister, were born when Hera touched a flower. A fierce warrior, he loved battle and often took part in conflicts between mortals. Ares killed Halirrhothios, son of Poseidon, when the youth violated his daughter, Alcippe. For this crime Ares was judged by a tribunal of the 12 Olympians and acquitted. The hill on which the trial took place, the Areopagus, was named for him. The worship of Ares was not as important as that of Mars, with whom he was identified by the Romans.