Wilhelm Richard Wagner was a German composer, conductor, music theorist and essayist, primarily known for his operas . Unlike most other great opera composers, Wagner wrote the scenario and libretto for his works.

Wagner's compositions, particularly those of his later period, are notable for contrapuntal texture, rich chromaticism, harmonies and orchestration, and elaborate use of leitmotifs: musical themes associated with particular characters, locales or plot elements. Wagner pioneered advances in musical language, such as extreme chromaticism and quickly shifting tonal centres, which greatly influenced the development of European classical music.