AEGISTHUS, in Ancient History, was the son of Thyestes by his own daughter Pelopea, who to conceal her shame exposed him in the woods. Some say he was taken up by a shepherd and suckled by a goat; whence he was called Aegisthus. After he grew up he was recognised by his father, and on the death of the latter he became king of Mycenae. He did not join the expedition against Troy; and after the departure of the expedition he seduced Clytemnestra, the wife of Agamemnon, and lived with her during the siege of Troy. Afterwards, with her assistance, he slew her husband, and reigned seven years in Mycenae. He was slain, together with Clytemnestra, by Orestes.