Lady Macbeth is the titular deuteragonist/secondary antagonist (arguably true main antagonist) of Shakespeare's play Macbeth. She is the wife of Lord Macbeth, and it is she who gives him the idea of killing the King.
Because of her part in the crimes, Lady Macbeth is so remorseful that she walks in her sleep and hangs herself to death.
In the opera, she is a soprano.
She was played by famous French actress Marion Cotillard in the 2015 adaptation of the play directed by Justin Kurzel.