Elektra
daughter of Agamemnon
Elektra of Mycenae was the daughter of King Agamemnon of Mycenae and Klytaimnestra. She had a brother, Orestes, and two sisters, Iphigeneia and Chrysothemis.
After the Trojan War, Agamemnon was killed by Klytaimnestra and her lover Aegisthos because Agamemnon sacrificed Iphigeneia for good winds to sail. Elektra helped Orestes to kill their mother Klytaimnestra and her lover, to avenge their father's death.
Wikimedia Commons has media related to Electra.