A son of Pelops and Hippodamia, a grandson of Tantalus, and a brother of Thyestes and Nicippe. He was first married to Cleola, by whom he became the father of Pleisthenes; then to Aerope, the widow of his son Pleisthenes, who was the mother of Agamemnon, Menelaus, and Anaxibia, either by Pleisthenes or by Atreus; and lastly to Pelopia, the daughter of his brother Thyestes.1

The tragic fate of the house of Tantalus gave ample materials to the tragic poets of Greece, but the oftener the subjects were handled, the greater were the changes and modifications which the legends underwent; but the main points are collected in Hyginus.

The story of Atreus begins with a crime, for he and his brother Thyestes were induced by their mother Hippodamia to kill their step-brother Chrysippus, the son of Pelops and the nymph Axioche or Danais.2 According to the Scholiast on Thucydides,3 who seems himself to justify the remark of his commentator, it was Pelops himself who killed Chrysippus. Atreus and Thyestes hereupon took to flight, dreading the consequences of their deed, or, according to the tradition of Thucydides, to escape the fate of Chrysippus. Sthenelus, king of Mycenae, and husband of their sister Nicippe (the Scholiast on Thucydides calls her Astydameia) invited them to come to Midea, which he assigned to them as their residence.4

When afterwards Eurystheus, the son of Sthenelus, marched out against the Heraclidae, he entrusted the government of Mycenae to his uncle Atreus; and after the fall of Eurystheus in Attica, Atreus became his successor in the kingdom of Mycenae. From this moment, crimes and calamities followed one another in rapid succession in the house of Tantalus.

Thyestes seduced Aerope, the wife of Atreus, and robbed him also of the lamb with the golden fleece, the gift of Hermes.5 For this crime, Thyestes was expelled from Mycenae by his brother; but from his place of exile he sent Pleisthenes, the son of Atreus, whom he had brought up as his own child, commanding him to kill Atreus. Atreus however slew the emissary, without knowing that he was his own son. This part of the story contains a manifest contradiction; for if Atreus killed Pleisthenes under these circumstances, his wife Aerope, whom Thyestes had seduced, cannot have been the widow of Pleisthenes.6

In order to obtain an opportunity for taking revenge, Atreus feigned to be reconciled to Thyestes, and invited him to Mycenae. When the request was complied with, Atreus killed the two sons of Thyestes, Tantalus and Pleisthenes, and had their flesh prepared and placed it before Thyestes as a meal. After Thyestes had eaten some of it, Atreus ordered the arms and bones of the children to be brought in, and Thyestes, struck with horror at the sight, cursed the house of Tantalus and fled, and Helios turned away his face from the frightful scene.7

The kingdom of Atreus was now visited by scarcity and famine, and the oracle, when consulted about the means of averting the calamity, advised Atreus to call back Thyestes. Atreus, who went out in search of him, came to king Thesprotus, and as he did not find him there, he married his third wife, Pelopia, the daughter of Thyestes, whom Atreus believed to be a daughter of Thesprotus. Pelopia was at the time with child by her own father, and after having given birth to a boy (Aegisthus), she exposed him. The child, however, was found by shepherds, and suckled by a goat; and Atreus, on hearing of his existence, sent for him and educated him as his own child. According to Aeschylus,8 Aegisthus, when yet a child, was banished with his father Thyestes from Mycenae, and did not return thither until he had grown up to manhood.

Afterwards, when Agamemnon and Menelaus had grown up, Atreus sent them out in search of Thyestes. They found him at Delphi, and led him back to Mycenae. Here Atreus had him imprisoned, and sent Aegisthus to put him to death. But Aegisthus was recognized by his father; and, returning to Atreus, he pretended to have killed Thyestes, and slew Atreus himself, who was just offering up a sacrifice on the sea-coast.9

The tomb of Atreus still existed in the time of Pausanias.10 The treasury of Atreus and his sons at Mycenae, which is mentioned by Pausanias,11 is believed by some to exist still;12 but the ruins which Müller there describes are above ground, whereas Pausanias calls the building ὑπόγαια (hypogaia).