Lady Macbeth is a character in Shakespeare's Macbeth (c. 1603–1607).

She is the wife to the play's protagonist, Macbeth, a Scottish nobleman. After goading him into committing regicide, she becomes Queen of Scotland, and later suffers pangs of guilt for her part in the crime. She dies off-stage in the last act, an apparent suicide. The character's origins lie in the accounts of Kings Duff and Duncan in Holinshed's Chronicles (1587), a history of Britain familiar to Shakespeare.

Shakespeare's Lady Macbeth appears to be a composite of two separate and distinct personages in Holinshed's work: Donwald's nagging, murderous wife in the account of King Duff, and Macbeth's ambitious wife in the account of King Duncan. Lady Macbeth is a powerful presence in the play, most notably in the first two acts. Following the murder of King Duncan however, her role in the plot diminishes. She becomes an uninvolved spectator to Macbeth's plotting, and a nervous hostess at a banquet dominated by her husband's thrilling hallucinations.

Her fifth act sleepwalking scene is a tour de force and her cry, "Out, damned spot! ," has become a phrase familiar to most speakers of the English language. The report of her death late in the fifth act provides the inspiration for Macbeth's "Tomorrow and tomorrow and tomorrow" speech. Analysts see in the character of Lady Macbeth the conflict between feminine and masculine, as they are impressed in cultural norms. Lady Macbeth suppresses her instincts toward compassion, motherhood, and fragility — associated with femininity — in favour of ambition, ruthlessness, and a lust for power.This conflict colours the entire drama, and sheds light on gender-based preconceptions from Shakespearean England to the present. The role has attracted countless notable actresses over the centuries including Sarah Siddons, Helen Faucit, Ellen Terry, Vivien Leigh, Francesca Annis, Judith Anderson, Judi Dench and Keeley Hawes.

Jeanette Nolan played the character in Orson Welles' controversial film adaptation of 1948.