Wilhelm Richard Wagner ( VAHG-nər; German: [ˈʁɪçaʁt ˈvaːɡnɐ] ; 22 May 1813 – 13 February 1883) was a German composer, theatre director, essayist, and conductor who is chiefly known for his operas (or, as some of his mature works were later known, "music dramas"). Unlike most opera composers, Wagner wrote both the libretto and the music for each of his stage works. Initially establishing his reputation as a composer of works in the romantic vein of Carl Maria von Weber and Giacomo Meyerbeer, Wagner revolutionised opera through his concept of the Gesamtkunstwerk ("total work of art"), whereby he sought to synthesise the poetic, visual, musical and dramatic arts, with music subsidiary to drama. The drama was to be presented as a continuously sung narrative, without conventional operatic structures like arias and recitatives. He described this vision in a series of essays published between 1849 and 1852. Wagner realised these ideas most fully in the first half of the 16-hour, four-opera cycle Der Ring des Nibelungen (The Ring of the Nibelung, also known simply as The Ring).

Wagner's compositions, particularly those of his later period, are notable for their complex textures, rich harmonies and orchestration, and the elaborate use of leitmotifs—musical phrases associated with individual characters, places, ideas, or plot elements. His advances in musical language, such as extreme chromaticism and quickly shifting tonal centres, greatly influenced the development of classical music; his Tristan und Isolde is regarded as an important precursor towards modern music. As he matured, he softened his ideological stance against traditional operatic forms (i.e., arias, ensembles and choruses), reintroducing them into his last few stage works, including Die Meistersinger von Nürnberg (The Mastersingers of Nuremberg) and Parsifal.

To properly present his vision of the works, Wagner had his own opera house built to his specifications: the Bayreuth Festspielhaus, which featured many innovative design elements intended to immerse the audience in the drama.