Aegisthus (ējĭsˈthəs) [key], in Greek mythology, according to most legends the incestuous offspring of Thyestes and his daughter Pelopia. At Thyestes' behest Aegisthus revenged the murder of his brothers by killing his uncle Atreus. Later, he was known as the lover of Clytemnestra and aided her in the murdering of her husband, Agamemnon. He was killed in revenge by Clytemnestra's son, Orestes.
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