A son of Thyestes, who unwittingly begot him by his own daughter Pelopia. Immediately after his birth he was exposed by his mother, but was found and saved by shepherds and suckled by a goat, whence his name Aegisthus (from αἴξ).1 Subsequently he was searched after and found by Atreus, the brother of Thyestes, who had him educated as his own child, so that every body believed Aegisthus to be his son.

In the night in which Pelopia had shared the bed of her father, she had taken from him his sword which she afterwards gave to Aegisthus. This sword became the means by which the incestuous intercourse between her and her father was discovered, whereupon she put an end to her own life. Atreus in his enmity towards his brother sent Aegisthus to kill him; but the sword which Aegisthus carried was the cause of the recognition between Thyestes and his son, and the latter returned and slew his uncle Atreus, while he was offering a sacrifice on the sea-coast. Aegisthus and his father now took possession of their lawful inheritance from which they had been expelled by Atreus.2

Homer appears to know nothing of all these tragic occurrences, and we learn from him only that, after the death of Thyestes, Aegisthus ruled as king at Mycenae and took no part in the Trojan expedition.3

While Agamemnon, the son of Atreus, was absent on his expedition against Troy, Aegisthus seduced Clytemnestra, the wife of Agamemnon, and was so wicked as to offer up thanks to the gods for the success with which his criminal exertions were crowned.4 In order not to be surprised by the return of Agamemnon, he sent out spies, and when Agamemnon came, Aegisthus invited him to a repast at which he had him treacherously murdered.5 After this event Aegisthus reigned seven years longer over Mycenae, until in the eighth Orestes, the son of Agamemnon, returned home and avenged the death of his father by putting the adulterer to death.6

Aschylus (525-456 BCE) used this theme for his trilogy of tragedies Oristeia, and Richard Strauss used it to compose his famous musical drama Elektra.



  1. Hyginus. Fabulae, 87, 88; Aelian. Varia Historia xii, 42.
  2. Hyginus, l.c., and 252.
  3. Odyssey iv, 518 ff.
  4. Homer. Odyssey iii, 263 ff.
  5. Homer. Odyssey iv, 524 ff.; Pausanias. Description of Greece ii, 16.5.
  6. 6.Homer. Odyssey i, 28 ff.; comp. Agamemnon, Clytemnestra, Orestes.


  • Smith, William. (1870). Dictionary of Greek and Roman Biography and Mythology. London: Taylor, Walton, and Maberly.

This article incorporates text from Dictionary of Greek and Roman Biography and Mythology (1870) by William Smith, which is in the public domain.