''Tristan and Iseult'': the OlderThanPrint tale of two StarCrossedLovers, namely Tristan/Tristram, a Cornish knight, and Iseult/Isolde, an Irish princess. Although she is married to his uncle Mark, a series of mishaps generally involving a LovePotion cause them to fall hopelessly in love. Emphasis on hopelessly. Various shenaningans ensue until their eventual, inevitable and very tragic deaths.

There may have been a historical basis to the legend, but it was largely the invention of medieval [[ChivalricRomance romancers]], who also decided that Tristan should be a Knight of the Round Table, as this was the proper place for talented knights who had affairs with their queens (''cf''. Lancelot and Guenevere). There are numerous versions of the legend, almost none of which end happily. It has spawned poems, plays, opera and even a [[Film/TristanAndIsolde recent film]].
!!This legend provides examples of:

* ArrangedMarriage
* CourtlyLove: Everyone knows CourtlyLove just means rampant adultery!
* DeathByDespair
* EverythingsBetterWithPrincesses
* GuileHero: Tristan, though he's very good with a sword. Isolde as well, for engineering one massive deception involving swearing under oath and ''holy relics''.
* HeroWorshipper: Fairly standard version given to Tristan by his squire Curvenal.
* InstantAwesomeJustAddDragons: Random dragon-slaying usually occurs.
* KickTheDog: Tristan manages to convince a neighboring king to part with a prized "fey dog" whose fur changed color and wore a magic bell. The net effect is to act as a CareBearStare that can cheer up anyone, which was for the king his sole comfort. So Tristan gives it to Iseult to help console her during his absences. The little dog comforts her... and she kills it, because she prefers to be in anguish over his absence than have a moment's comfort.
** Note that in some versions it's just the chime of the bell that will bring one hapinesss -- Iseult throws the bell into the sea for the above-mentioned reason but keeps the dog as a reminder of her beloved.
** Mark also gets a rather literal one: after Tristan and Iseult have run off together, he tries to hang Tristan's dog.
* KingArthur
* LoveTriangle: Fairly standard--Tristan, Iseult, his uncle.
** Although, include secondary characters in amorous pursuit of one or the other eponymous characters such as [[spoiler:Iseult White Hands, Palomides, Bellise, a Steward, Karhedins]], and you have yourself a LoveDodecahedron.
* LoopholeAbuse: One version has KingArthur decide Iseult will be with Tristan when the trees bear leaves and with Mark when they don't (i.e. winter). Iseult then joyfully remembers the existence of evergreens.
* LoveMakesYouCrazy: Tristan goes mad when he thinks Iseult is cheating on him with his [[BestFriendsInLaw friend]] Kahedrin.
* LovePotion: One is prepared for Iseult in order to make her ArrangedMarriage to Mark work out. So of course Tristan drinks it by mistake, falling in love with Iseult.
* MeaningfulName: Tristan's name is explained in-story as derived from the French "triste", meaning "sad" or "sorrowful". In reality, it's derived from the Pictish name "Drystan" (latinized "Drustanus").
* OneSteveLimit: There is another Iseult. [[spoiler: She marries Tristan and often brings about his death]]
* PortmanteauCoupleName: In-universe. Iseult's brother Alcardo renames himself Lantris after the two greatest knights in the world, Tristan and Lancelot.
* ProtagonistCenteredMorality: Tristan and Isolde are guilty of horrible crimes by Medieval standards -sleeping with the king's wife is a blatant case of treason. Yet it is the barons of king Mark, who correctly suspects the adultery, whom the narrator refers to as "traitors" -all because they are loyal to their king and try to catch the protagonists for a crime they did and continue to do. Also, then the "traitors" demand that Isolde go through an ordeal to prove her innocence she avoids lying by a clever technicality (ExactWords) and God himself covers for her by miraculously letting her hold red-hot iron without hurting her hands.
* SpellMyNameWithAnS: Iseult's name has been spelled in too many ways to count. The most popular are probably "Isolde" and "Isolda".
* StarCrossedLovers: The eponymous couple.
* TheLancer: Dinadan often acts as this for Tristan.
* TogetherInDeath: [[spoiler:In many versions, a hazel tree springs from Tristan's grave and a honeysuckle twines around it from Iseult's grave. Aww. (In some versions it's a briar and a rose - a trope of its own which echoes down through folksongs to the present day.)]]
* TreacherousAdvisor: The three nobles who are jealous of Tristan.
* WithFriendsLikeThese: While Tristan has a lot of friends, he is also prone to spectacular fallings out with them, usually when they develop crushes on Iseult (Even Lancelot does this at one point). The only friend he seems to be able to stay friends with is Gorvenal.