A leitmotif ( /ˌlaɪtmoʊˈtiːf/), sometimes written leit-motif, is a musical term (though occasionally used in theatre or literature), referring to a recurring theme, associated with a particular person, place, or idea. It is closely related to the musical idea of idée fixe. The term itself comes from the German Leitmotiv, literally meaning "leading motif", or perhaps more accurately, "guiding motif."

In particular such a theme should be 'clearly identified so as to retain its identity if modified on subsequent appearances' whether such modification be in terms of rhythm, harmony, orchestration or accompaniment. It may also be 'combined with other leitmotifs to suggest a new dramatic condition' or development. The technique is notably associated with the operas of Richard Wagner, although he was not its originator, and did not employ the word in connection with his work.

Although usually a short melody, it can also be a chord progression or even a simple rhythm. Leitmotifs can help to bind a work together into a coherent whole, and also enable the composer to relate a story without the use of words, or to add an extra level to an already present story.

Wilhelm Richard Wagner ( /ˈvɑːɡnər/; German pronunciation: [ˈʁiçaʁt ˈvaːɡnɐ]; 22 May 1813 – 13 February 1883) was a German composer, conductor, theatre director and polemicist primarily known for his operas (or "music dramas", as he later called them). Wagner's compositions, particularly those of his later period, are notable for their complex texture, rich harmonies and orchestration, and the elaborate use of leitmotifs: musical themes associated with individual characters, places, ideas or plot elements. Unlike most other opera composers, Wagner wrote both the music and libretto for every one of his stage works. Perhaps the two best-known extracts from his works are the Ride of the Valkyries from the opera Die Walküre, and the Wedding March (Bridal Chorus) from the opera Lohengrin.

Initially establishing his reputation as a composer of works such as The Flying Dutchman and Tannhäuser which were broadly in the romantic vein of Weber and Meyerbeer, Wagner transformed operatic thought through his concept of the Gesamtkunstwerk ("total work of art"). This would achieve the synthesis of all the poetic, visual, musical and dramatic arts and was announced in a series of essays between 1849 and 1852. Wagner realized this concept most fully in the first half of the monumental four-opera cycle Der Ring des Nibelungen. However, his thoughts on the relative importance of music and drama were to change again, and he reintroduced some traditional operatic forms into his last few stage works, including Die Meistersinger von Nürnberg.