Agamemnon, in Greek mythology, King of Mycenae and commander of the Greek forces in the Trojan War. He was the son of Atreus and suffered under the curse laid on his house (see Atreus, House of). When the Greeks had assembled in Aulis for their voyage to Troy, they were held back by adverse winds. To calm the winds, Agamemnon sacrificed his daughter Iphigenia to the goddess Artemis. His quarrel with Achilles over the captive princess Briseis and the consequences of that quarrel form much of the plot of the Iliad by Homer. After a ten-year siege, Troy fell and Agamemnon returned in triumph to Mycenae. With him came the Trojan princess Cassandra, who had been awarded to him by the victorious Greek army.

Clytemnestra, Agamemnon's wife, greeted him with protestations of love, but while he was in his bath she killed him with the assistance of her lover Aegisthus. His death was avenged seven years later by his son Orestes. The story of Agamemnon's death is told in the first play of the trilogy Oresteia, by the ancient Greek poet Aeschylus.