thumb|Tristan and Isolde by [[Herbert James Draper|Herbert Draper (1901)]]
Tristan and Iseult, also known as Tristan and Isolde and other names, is a medieval legend told in numerous variations since the 12th century. Of disputed source, usually assumed to be primarily Celtic, the tale is a tragedy about the illicit love between the Cornish<!-- Don't change this without agreement on talk --> knight Tristan and the Irish princess Iseult in the days of King Arthur. During Tristan's mission to escort Iseult from Ireland to marry his uncle, King Mark of Cornwall, Tristan and Iseult ingest a love potion, instigating a forbidden love affair between them. Depending on the version, Tristan may marry another woman, Iseult of the White Hands, but never stops loving the Irish princess. The tale typically ends in their deaths from love and sorrow.
The legend has had a strong and lasting impact on Western culture. Its different versions exist in many European texts in various languages from the Middle Ages. The earliest instances take two primary forms: the so-called courtly and common branches, respectively associated with the 12th-century poems of Thomas of Britain and Béroul, the latter believed to reflect a now-lost original tale. A subsequent version emerged in the 13th century in the wake of the greatly expanded Prose Tristan, merging Tristan's romance more thoroughly with the Arthurian legend. Finally, after the revived interest in the medieval era in the 19th century under the influence of Romantic nationalism, the story has continued to be popular in the modern era, notably through Wagner's operatic adaptation.
Narratives
The story and character of Tristan varies considerably between different tellings. His name also varies, as does that of Iseult, although Tristan is the most common modern spelling.
The two earliest known, and highly distinct from one another, traditions of the romance of Tristan and Iseult come from the French verse romances written by Béroul and Thomas of Britain (considered origins of the so-called "common branch" and the "courtly branch", respectively), two 12th-century poets who each wrote , based on uncertain origins. A later major tradition is that of cyclical prose works beginning , markedly different from those by both Thomas and Béroul.
Early poetry
thumb|left|Tristan and Isolde by [[John Duncan (painter)|John Duncan (1912)|alt=]]
After defeating the Irish knight Morholt in a duel, the young prince Tristan travels to Ireland to bring back the fair Iseult (often known as Isolde, Isolt, or Yseult) to marry his uncle King Mark of Cornwall (originally written as Marc or Marc'h). Along the way, Tristan and Iseult ingest a love potion, which causes them to fall madly in love. The potion's effects last a lifetime in the legend's so-called courtly branch. However, in the common branch version (Béroul's), the potion's results end after three years.
In some versions, including Béroul's, Tristan and Iseult ingest the potion accidentally after it was given to her by her mother to use on her wedding night. In others, the potion's maker gives it to Iseult to share with Mark, but she gives it to Tristan instead. Although Iseult marries Mark, the spell forces her and Tristan to seek each other as lovers. The King's advisors repeatedly try to charge the pair with adultery, but the lovers use trickery to preserve their façade of innocence.
In Béroul's poem, the love potion eventually wears off, but the two lovers continue their adulterous relationship for some time, until returning to the kingdom of Cornwall, where King Mark is alerted to the affair by the machinations of three of his barons (one of them called Ganelon, in a possible nod to the famous traitor) and then seeks to entrap his nephew and wife. Mark acquires what seems to be proof of their guilt and resolves to punish Tristan by hanging and Iseult by burning at the stake. However, Mark changes his mind about Iseult and lodges her in a leper colony. Tristan escapes on his way to the gallows, making a miraculous leap from a chapel to rescue Iseult. The lovers flee into the forest of Morois (or Morrois) and take shelter there for several years until Mark later discovers them and takes pity on their exile and suffering. They make peace with Mark after Tristan agrees to return Iseult to Mark and leave the country. According to Danielle Quéruel of the Bibliothèque nationale de France (abridged from a French article),