Atreus (ā´trēəs), in Greek mythology, the son of Pelops and the father of Agamemnon and Menelaus. He vied with his brother Thyestes for the throne of Mycenae. When Thyestes seduced Atreus' wife, Aerope, in order to attain the golden ram whose possession signified kingship, Atreus, in retaliation, murdered the sons of Thyestes and served them to him at a feast. Thyestes thereupon laid a curse upon the house of Atreus. Thyestes' son Aegisthus, who was not involved in the mass murder, killed Atreus and restored the kingdom to Thyestes.