Clytemnestra murders her husband when he finally returns from Troy. What most retellings gloss over is exactly why — and the fact that her own reasoning, voiced directly in the oldest surviving version of her story, is a genuinely coherent case for revenge rather than simple malice.
Before sailing for Troy, Agamemnon needed favourable winds for his fleet — and to secure them, he lured his own daughter Iphigenia to Aulis under the pretence of marrying her to Achilles, then sacrificed her to the goddess Artemis. In the tragic tradition established by Aeschylus, the sacrifice is completed, not averted. Clytemnestra spends the following ten years of Agamemnon's absence at Troy with this grievance entirely unresolved.
When Agamemnon finally returns — bringing the prophetess Cassandra with him as a war-prize concubine, a fresh insult layered on top of the old grievance — Clytemnestra kills him, in Aeschylus's staging trapping him in a net-like robe while he bathes and stabbing him repeatedly. She kills Cassandra alongside him. In her own voice, as Aeschylus writes it, this is not simply cruelty — it is a mother's deliberate reckoning for a murdered daughter, delivered on the man responsible.
A revenge that doesn't end with her: Clytemnestra's own children, Orestes and Electra, do not accept their father's murder as settled justice. Orestes ultimately kills Clytemnestra and her lover Aegisthus in turn — continuing the House of Atreus's generational cycle of blood vengeance rather than resolving it.
A mythic origin point for formal justice: Orestes's matricide is itself so morally fraught — is killing your mother ever justified, even in revenge for your father? — that Aeschylus's Oresteia resolves it not with another killing but with an invention: Athena establishes a formal court, the Areopagus, to try Orestes by jury rather than allow the family's cycle of vengeance to continue indefinitely. Ancient Greek tragedy uses Clytemnestra's own act of revenge as the mythic hinge point where blood vengeance is replaced, for the first time, by formal legal judgment.
Costanza Casati's 2023 novel Clytemnestra is among the most notable recent efforts to restore her own coherent, sympathetic motivation to the centre of the story, rather than treating her simply as the villain of her husband's homecoming.