Don Juan (Spanish: [doŋ ˈxwan]), also known as Don Giovanni (Italian), is a legendary, fictional Spanish libertine who devotes his life to seducing women. Famous versions of the story include a 17th-century play, El burlador de Sevilla y convidado de piedra (The Trickster of Seville and the Stone Guest) by Tirso de Molina, a 1787 opera, Don Giovanni, with music by Mozart and a libretto by Lorenzo da Ponte, and a satirical, epic poem, Don Juan, by Lord Byron.

By linguistic extension, from the name of the character, "Don Juan" has become a generic expression for a womanizer, and stemming from this, Don Juanism is a non-clinical psychiatric descriptor.