Aegisthus was a figure in Greek mythology. Aegisthus is known from two primary sources: the first is Homer's Odyssey, believed to have been first written down by Homer at the end of the 8th century BC, and the second from Aeschylus's Oresteia, written in the 5th century BC. Aegisthus also features heavily in the action of Euripides's Electra, although his character remains offstage.

In Greek mythology, Thyestes was a king of Olympia. Thyestes and his brother, Atreus, were exiled by their father for having murdered their half-brother, Chrysippus, in their desire for the throne of Olympia. They took refuge in Mycenae, where they ascended the throne upon the absence of King Eurystheus, who was fighting the Heracleidae. Eurystheus had meant for their lordship to be temporary; it became permanent because of his death in conflict.