aegisthus

noun Classical Mythology.

1. a cousin of Agamemnon who seduced Clytemnestra, Agamemnon’s wife, and was later killed by Orestes.

noun

1. Greek myth a cousin to and the murderer of Agamemnon, whose wife Clytemnestra he had seduced. He usurped the kingship of Mycenae until Orestes, Agamemnon’s son, returned home and killed him