Carmen is an opera in four acts by the French composer Georges Bizet. The libretto was written by Henri Meilhac and Ludovic Halévy, based on a novella of the same title by Prosper Mérimée. The opera was first performed at the Opéra-Comique in Paris, on 3 March 1875, and at first was not particularly successful. Its initial run extended to 36 performances, before the conclusion of which Bizet died suddenly, and thus knew nothing of the opera's later celebrity.

The opera, written in the genre of opéra comique with musical numbers separated by dialogue, tells the story of the downfall of Don José, a naïve soldier who is seduced by the wiles of the fiery Gypsy, Carmen. José abandons his childhood sweetheart and deserts from his military duties, yet loses Carmen's love to the glamorous toreador Escamillo, after which José kills her in a jealous rage. The depictions of proletarian life, immorality and lawlessness, and the tragic death of the main character on stage, broke new ground in French opera and were highly controversial. After the premiere, most reviews were critical, and the French public was generally indifferent. Carmen initially gained its reputation through a series of productions outside France, and was not revived in Paris until 1883; thereafter it rapidly acquired celebrity at home and abroad, and continues to be one of the most frequently performed operas; the "Toreador song" from act 2 is among the best known of all operatic arias. Later commentators have asserted that Carmen forms the bridge between the tradition of opéra comique and the realism or verismo that characterised late 19th-century Italian opera.

The music of Carmen has been widely acclaimed for its brilliance of melody, harmony, atmosphere and orchestration, and for the skill with which Bizet musically represented the emotions and suffering of his characters. After the composer's death the score was subject to significant amendment, including the introduction of recitative in place of the original dialogue; there is no standard edition of the opera, and different views exist as to what versions best express Bizet's intentions. The opera has been recorded many times since the first acoustical recording in 1908, and the story has been the subject of many screen and stage adaptations.