A femme fatale ( or ; French: [fam fatal]), sometimes called a maneater or vamp, is a stock character of a mysterious, beautiful, and seductive woman whose charms ensnare her lovers, often leading them into compromising, deadly traps. She is an archetype of literature and art. Her ability to enchant, entice and hypnotize her victim with a spell was in the earliest stories seen as verging on supernatural; hence, the femme fatale today is still often described as having a power akin to an enchantress, seductress, witch, having power over men. Femmes fatales are typically villainous, or at least morally ambiguous, and always associated with a sense of mystification, and unease.

The term originates from the French phrase femme fatale, which means 'deadly woman' or 'lethal woman'. A femme fatale tries to achieve her hidden purpose by using feminine wiles such as beauty, charm, or sexual allure. In many cases, her attitude towards sexuality is lackadaisical, intriguing, or frivolous. In some cases, she uses lies or coercion rather than charm. She may also make use of some subduing weapon such as sleeping gas, a modern analog of magical powers in older tales. She may also be (or imply that she is) a victim, caught in a situation from which she cannot escape. A younger or underage version of a femme fatale is called a fille fatale, from the French phrase for 'deadly girl'.

In American early 20th-century films, a femme fatale character was referred to as a vamp, a reference to The Vampire, Philip Burne-Jones's 1897 painting, and Rudyard Kipling's later 1897 poem, and the 1909 play and 1915 film A Fool There Was.

Female mobsters (including Italian-American Mafia or Russian Mafia) have been portrayed as femmes fatales in films noir. Femmes fatales appear in James Bond films.