In Greek mythology, Aegisthus killed Agamemnon after the king returned from the Trojan War. Aegisthus was Agamemnon’s cousin and the lover of Agamemnon’s wife, Clytemnestra.
While Agamemnon led the Greek expedition against Troy, Aegisthus remained in Mycenae and began an affair with Clytemnestra. In the tragic tradition, the pair planned revenge because Agamemnon had sacrificed their daughter Iphigenia before the fleet sailed.
Aegisthus and Clytemnestra murdered Agamemnon during or soon after his homecoming. Different ancient authors vary on the exact method, including accounts involving a bath, a robe, or a weapon.
Agamemnon’s son Orestes later avenged the murder by killing both Aegisthus and Clytemnestra. Their story became a major subject for Greek tragedians, especially Aeschylus, Sophocles, and Euripides.