Clytemnestra (or Clytaemnestra) is the wife of Agamemnon and queen of Mycenae.
While Agamemnon was away at the Trojan War, Clytemnestra took a lover: Aegisthus, who was Agamemnon's cousin. Some sources say that Clytemnestra waited a long time for Agamemnon to return before taking a lover, but when his ship was blown off course on return to Troy, she was eventually seduced.
During the war, Agamemnon sent home for his daughter, Iphigeneia. He told Clytemnestra that she would be wed to Achilles, but he would instead sacrifice her to Artemis to ensure his victory in the war.
When Agamemnon returned victorious after the Trojan War, Clytemnestra was furrious both for the death of her daughter and for Agamemnon's new concubine, Cassandra. She killed Agamemnon and Cassandra, and made Aegisthus King of Mycenae.
Her son, Orestes, later avenged his father's death, possibly with the help of Electra.