Aegisthus

According to the traditions cited, an oracle told Thyestes that the way to regain the throne was for him to father a son by Pelopia; Thyestes raped Pelopia, she bore a son who was abandoned, and the infant was raised by shepherds and suckled by a goat, an origin that gave him the name Aegisthus (from αἴξ, 'male goat'). In some accounts that son later returns and slays his uncle Atreus, restoring Thyestes to power; other narratives emphasize his later relationship with Clytemnestra and his role in the murder of Agamemnon and subsequent rule of Mycenae until Orestes' return and vengeance.

Primary sources and the supplied summaries do not provide a detailed physical description. Dramatic portrayals (notably Aeschylus' Oresteia as read by modern commentators) characterize him by temperament rather than fixed corporeal traits: Aeschylus depicts him as relatively weak and effeminate in role (a 'weak lion' in some modern summaries), often the plotting but passive partner to the more active Clytemnestra. In performance traditions he is commonly assigned a baritone vocal range in operatic settings.

No supernatural abilities are attributed in the provided materials. His capacities are political and interpersonal: he can conspire, seduce (becoming Clytemnestra's lover while Agamemnon is at Troy), commit or partake in murder (sources record him killing Atreus in one account and collaborating in Agamemnon's killing), and hold royal power (he rules Mycenae for seven years after Agamemnon's death in the cited summaries). His agency principally operates within human schemes of vengeance and dynastic contestation.