Mourning Becomes Electra is the title for a trilogy of plays by Eugene O'Neill, first performed in 1931. In 1947 the play was made into a movie by Dudley Nichols. In 1967, the Metropolitan Opera gave the world premiere of an operatic version, composed by Martin David Levy to the libretto of William Henry Butler. Both film and opera retain O'Neill's title.

It updates the Greek myth of Orestes to the family of a Northern general in the American Civil War. Agamemnon is now General Ezra Mannon, Clytemnestra is his second wife Christine, Orestes is his son Orin, and Electra is his daughter Lavinia. As an updated Greek tragedy, the play features murder, adultery, incestuous love and revenge, and even a group of townspeople who function as a kind of Greek chorus. Though fate alone guides characters' actions in Greek tragedies, O'Neill's characters have motivations grounded in 1930s-era psychological theory as well. The play can easily be read from a Freudian perspective, paying attention to various characters' Oedipus complexes and Electra complexes.

Mourning Becomes Electra is divided into three plays with themes corresponding to The Oresteia trilogy by Aeschylus. In order, the three plays are titled Homecoming, The Hunted, and The Haunted. However, these plays are never produced individually, but only as part of the larger trilogy. Each of these plays contain four to five acts, and so Mourning Becomes Electra is extraordinarily lengthy for a drama. In production, it is often cut down. Also, because of the large cast size, it is not performed as often as some of O'Neill's other major plays.

The 1947 film version starred Rosalind Russell, Michael Redgrave, Raymond Massey, Katina Paxinou, Leo Genn and Kirk Douglas. It was nominated for Academy Awards for Best Actor in a Leading Role (Michael Redgrave) and Best Actress in a Leading Role (Rosalind Russell). Originally released by RKO at nearly three hours, it was eventually edited down to 105 minutes (losing more than an hour) after it performed poorly at the box office and won no Oscars. It has since been restored to its full length and shown on Turner Classic Movies.

A notorious Oscar upset occurred in connection with the film. All who saw it had taken it for granted that Rosalind Russell would win for her performance as Lavinia, to the point that Russell actually began to rise from her seat just before the winner's name was called. However, it was Loretta Young, and not Ms. Russell, who was named Best Actress (for her performance in The Farmer's Daughter).

While forgotten in the US, it was shown on British TV in the early 1960's and given such good reviews that was actually released in the movie theatres.

Eugene O'Neill's updated version of the Orestaia. In New England, after the American Civil War, a war-weary Agamem--er, Ezra Mannon comes home to his unhappy wife (Christine) and loving daughter (Lavinia). But Lavinia's ex-suitor, Adam Brant, has become Christine's lover, and together Adam and Christine plot to poison Ezra. When they succeed, Lavinia turns to her brother Orin to help bring the lovers to justice, but when they succeed, Orin goes mad and his suicide note may come between Lavinia and her new suitor, Peter Niles. Written by Kathy Li