Introduction
Clytemnestra was the wife of Agamemnon, king of Mycenae, and — in the tradition that makes her the twin sister of Helen — a daughter of Zeus and Leda, though her own household affiliation is with the House of Atreus by marriage.
Family
Revenge and Retribution
Agamemnon's sacrifice of their daughter Iphigenia at Aulis left Clytemnestra with an implacable hatred of her husband. During his decade away at Troy she took Aegisthus, a cousin of Agamemnon with his own grievance against the house, as a lover and co-conspirator. When Agamemnon returned, the two murdered him; Clytemnestra was in turn killed years later by her own son Orestes, avenging his father — an act that entangles Orestes in the pursuing Furies and one of Greek tragedy's central moral crises.
As with all figures of Greek heroic legend, sources diverge on many particulars; the account above follows the most widely transmitted classical tradition.