The Tristan chord is a chord made up of the notes F, B, D♯ and G♯. More generally, it can be any chord that consists of these same intervals: augmented fourth, augmented sixth, and augmented ninth above a root. It is so named as it is heard in the opening phrase of Richard Wagner's opera Tristan und Isolde as part of the leitmotif relating to Tristan.

The notes of the Tristan chord are not unusual; they could be re-spelled to form a conventional half-diminished seventh chord. What distinguishes the chord is its unusual relationship to the implied key of its surroundings. At the time Tristan und Isolde was first heard (1865), the chord was considered innovative, disorienting, and daring. Musicians of the twentieth century often identify the chord as a starting point for the modernist disintegration of tonality.

This motif also appears in measures 6, 10, and 12, several times later in the work and at the end of the last act. Much has been written about its possible harmonic functions or voice leading (melodic function), and the motif has been interpreted in various ways. For instance, Schering (1935) traces the development of the Tristan chord through ten intermediate steps, beginning with the Phrygian cadence (iv6-V). Vogel points out the "chord" in earlier works by Guillaume de Machaut, Carlo Gesualdo, Bach, Mozart, Beethoven, or Louis Spohr, as in the following example from Beethoven's Piano Sonata No. 18, tempo allegro (see *):

Tristan /ˈtrɪstən/ (Latin/Brythonic: Drustanus; Welsh: Drystan, Trystan; also known as Tristran, Tristram /ˈtrɪstrəm/, etc.) is one of the main characters of the Tristan and Iseult story, a Cornish hero and one of the Knights of the Round Table featuring in the Matter of Britain. He is the son of Blancheflor and Rivalen (in later versions Isabelle and Meliodas), and the nephew of King Mark of Cornwall, sent to fetch Iseult back from Ireland to wed the king. However, he and Iseult accidentally consume a love potion while en route and fall helplessly in love. The pair undergo numerous trials that test their secret affair.

Tristan makes his first medieval appearance in the early twelfth century in Celtic folklore circulating in the north of France, and Brittany in particular, which had close ancestral and cultural links with Cornwall by way of the ancient British kingdom of Dumnonia, as made clear in the story itself. Although the oldest stories concerning Tristan are lost, some of the derivatives still exist. Most early versions fall into one of two branches, the "courtly" branch represented in the retellings of the Anglo-Norman poet Thomas of Britain and his German successor Gottfried von Strassburg, and the "common" branch, including the works of the French poet Béroul and the German poet Eilhart von Oberge.

Stephen John Fry (born 24 August 1957) is an English actor, screenwriter, author, playwright, journalist, poet, comedian, television presenter, film director, and a director of Norwich City Football Club.

After a troubled childhood and adolescence, during which he was expelled from a number of schools and eventually spent three months in prison for credit card fraud, he was able to secure a place at Queens' College, Cambridge, where he studied English Literature.

He first came to public attention in the 1981 Cambridge Footlights Revue presentation "The Cellar Tapes", which also included Hugh Laurie, Emma Thompson and Tony Slattery. With Hugh Laurie, as the comedy double act Fry and Laurie, he co-wrote and co-starred in A Bit of Fry & Laurie, and took the role of Jeeves (with Laurie playing Wooster) in Jeeves and Wooster.

As an actor, Fry played the lead in the film Wilde, was Melchett in the BBC television series Blackadder, starred as the title character Peter Kingdom in the ITV series Kingdom, has a recurring guest role as Dr. Gordon Wyatt on the Fox crime series Bones and appeared as rogue TV host Gordon Deitrich in the dystopian thriller V For Vendetta. He has also written and presented several documentary series including the 2008 television series Stephen Fry in America, which saw him travelling across all 50 US states. Since 2003 he has been the host of the quiz show QI.

Louis Spohr (5 April 1784 – 22 October 1859), born Ludwig Spohr, was a German composer, violinist and conductor. Highly regarded during his lifetime, Spohr published nine symphonies, ten operas, fifteen violin concerti, four clarinet concerti, and various works for small ensemble. Spohr was the inventor of both the violin chinrest and the orchestral rehearsal mark. His output occupies a pivotal position between Classicism and Romanticism, but fell into obscurity following his death. It is now rarely heard.

Spohr was born in Braunschweig in the duchy of Brunswick-Wolfenbüttel to Karl Heinrich Spohr and Juliane Ernestine Luise Henke. Spohr's first musical encouragement came from his parents: his mother was a gifted singer and pianist, and his father played the flute. A violinist named Dufour gave the lad his earliest violin teaching. The pupil's first attempts at composition date from the early 1790s. Dufour, recognizing the boy's musical talent, persuaded his parents to send him to Brunswick for further instruction.

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.