Perlesvaus, also called Li Hauz Livres du Graal (The High History of the Holy Grail), is an Old French Arthurian romance dating to the first decade of the 13th century. It purports to be a continuation of Chrétien de Troyes unfinished Perceval, the Story of the Grail, but it has been called the least canonical Arthurian tale because of its striking differences from other versions. It survives in three manuscripts, two fragments, and two 16th-century printings.
Perlesvaus begins by explaining that its main character, Percival, did not fulfill his destiny of achieving the Holy Grail because he failed to ask the Fisher King the question that would heal him, events related in Chrétien's work. The author soon digresses into the adventures of knights like Lancelot and Gawain, many of which have no analogue in other Arthurian literature. Often events and depictions of characters are thoroughly at odds with other versions of the story. For instance, while later literature depicts Loholt as a good knight and illegitimate son of King Arthur, in Perlesvaus he is apparently the legitimate son of Arthur and Guinevere, and he is slain treacherously by Arthur's seneschal Kay, who is elsewhere portrayed as a boor and a braggart but always as Arthur's loyal servant (and often, foster brother). Kay is jealous when Loholt kills a giant, so he murders him to take the credit. This backfires when Loholt's head is sent to Arthur's court in a box that can only be opened by his murderer. Kay is banished, and joins with Arthur's enemies, Brian of the Isles and Meliant. Guinevere expires upon seeing her son dead, which alters Arthur and Lancelot's actions substantially from what is found in later works.
Though its plot is frequently at variance with the standard Arthurian outline, Perlesvaus did have an effect on subsequent literature. Arthur's traditional enemies Claudas, Brian and Meliant appear for the first time in its pages, as does the Questing Beast (though in a radically different guise than it would take). The story of Kay murdering Loholt is mentioned in the Lancelot-Grail cycle as the one evil deed Kay ever committed, but the details and retribution are left out. Perlesvaus was adapted into Middle Welsh as part of Y Seint Greal, and one episode was rewritten in verse and included in Fouke Fitz Warin.