Electra is the daughter of Agamemnon and Clytemnestra, the king and queen of Mycenae. She is absent from Homer's epics, but appears in the Oresteia and in later Athenian plays.
In Aeschylus' play, the Libation Bearers, she supports her brother Orestes in his killing of their mother, Cltaemnestra as revenge for her killing of Agamemnon. In Electra by Euripides, she is depicted as more jealous and hateful (as are most of Euripides' female characters) and actually helps Orestes kill their mother.