Perlesvaus, (also The High History of the Holy Grail), is a French Arthurian romance dating to the first decade of the 13th century. It purports to be a continuation of Chrétien de Troyes unfinished Perceval (romance), but veers off wildly from traditional sources. The author is unknown.
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. The author soon digresses into the adventures of knights like Lancelot and Gawain, many of which have no analogue in other Arthurian literature.
For instance, while later literature depicts Loholt as the illegitimate son of King Arthur, in Perlesvaus he is son of Arthur and Guinevere, and is slain by Arthur's seneschal Kay, usually portrayed as something of a boor but loyal.
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 enemies Claudas, Brian and Meliant appear for the first time in its pages, as does the Questing Beast (though radically different from its later appearances).