Mourning Becomes Electra is a trilogy of plays written by American playwright Eugene O'Neill. The plays are based on the Greek myth of Electra and Orestes, and explore themes of revenge, justice, and the consequences of one's actions. The title of the trilogy is derived from the phrase 'mourning becomes Electra, ' which is a reference to the mourning of Electra for her father Agamemnon, who was killed by her mother Clytemnestra.