Armide is an opera by Christoph Willibald Gluck, set to a libretto by Philippe Quinault. Gluck's fifth production for the Parisian stage and the composer's own favourite among his works, it was first performed on 23 September 1777 by the Académie Royale de Musique in the second Salle du Palais-Royal in Paris.

Gluck set the same libretto Philippe Quinault had written for Lully in 1686, based on Torquato Tasso's Gerusalemme liberata (Jerusalem Delivered). Gluck seemed at ease in facing French traditions head-on when he composed Armide. Lully and Quinault were the very founders of serious opera in France and Armide was generally recognized as their masterpiece, so it was a bold move on Gluck's part to write new music to Quinault's words. A similar attempt to write a new opera to the libretto of Thésée by Jean Joseph de Mondonville in 1765 had ended in disaster, with audiences demanding it be replaced by Lully's original. By utilizing Armide, Gluck challenged the long-standing and apparently inviolable ideals of French practice, and in the process he revealed these values capable of renewal through "modern" compositional sensitivities. Critical response and resultant polemic resulted in one of those grand imbroglios common to French intellectual life. Gluck struck a nerve in French sensitivities, and whereas Armide was not one of his more popular works, it remained a critical touchstone in the French operatic tradition and was warmly praised by Berlioz in his Memoirs. Gluck also set a minor fashion for resetting Lully/Quinault operas: Gluck's rival Piccinni followed his example with Roland in 1778 and Atys in 1780; in the same year, Philidor produced a new Persée; and Gossec offered his version of Thésée in 1782. Gluck himself is said to have been working on an opera based on Roland, but he abandoned it when he heard Piccinni had taken on the same libretto.

The first modern revival of Armide was presented at the Théâtre National de l’Opéra (now named the Opéra National de Paris) in 1905 with Lucienne Bréval in the title role. Other cast members included Alice Verlet, Agustarello Affré, Dinh Gilly, and Geneviève Vix.