in Greek legend, the son of Pelops of Mycenae and his wife, Hippodamia. Atreus was the elder brother of Thyestes and was the king of Mycenae. The story of his family--the House of Atreus--is virtually unrivaled in antiquity for complexity and corruption.
A curse, said to have been pronounced by Myrtilus, a rival who died by Pelops' hand, plagued the descendants of Pelops. His sons Alcathous, Atreus, and Thyestes set upon a bloody course with the murder of their stepbrother Chrysippus, the son of Pelops' union with a nymph. After the crime the three brothers fled their native city of Pisa; Alcathous went to Megara, and Atreus and Thyestes stopped at Mycenae, where Atreus became king. But Thyestes either contested Atreus' right to rule or seduced Atreus' wife, AŽrope, and thus was driven from Mycenae. To avenge himself, Thyestes sent Pleisthenes (Atreus' son, whom Thyestes had brought up as his own) to kill Atreus, but the boy was himself slain, unrecognized by his father.
When Atreus learned the identity of the boy, he recalled Thyestes to Mycenae in apparent reconciliation. At a banquet Atreus served Thyestes the flesh of Thyestes' own son (or sons), whom Atreus had slain in vengeance for the death of Pleisthenes (or because of Thyestes' and Aerope's adultery). Thyestes fled in horror to Sicyon; there he impregnated his own daughter Pelopia in the hope of raising one more son to avenge himself. Atreus subsequently married Pelopia, and she afterward bore Aegisthus. Atreus believed this child to be his own, but Aegisthus was in fact the son of Thyestes.
Later, Agamemnon and Menelaus--sons of Atreus and AŽrope--found Thyestes and imprisoned him at Mycenae. Aegisthus was sent to murder Thyestes, but each recognized the other because of the sword that Pelopia had taken from her father and given to her son. Father and son slew Atreus, seized the throne, and drove Agamemnon and Menelaus out of the country.