A large body of writings in various languages in the 12th and 13th centuries and thereafter, recounting legends of King Arthur, his sword Excalibur, his queen Guinevere, and his various knights at the court of Camelot. The historical Arthur, if he existed, seems to have been some kind of chieftain in 6th‐century Wales. Literary legends about him and his deadly struggle with his treacherous nephew Modred or Mordred began with Geoffrey of Monmouth's Historia Regum Britanniae (c.1138). The Norman poet Wace expanded this account in his Roman de Brut (1155), which introduced the Round Table and the belief in Arthur's eventual resurrection. Wace's story was in turn extended in the early 13th century in the first English version of the legend, the verse history Brut by the priest Layamon, who adds the passing of Arthur by boat to Avalon. Meanwhile the French poet Chrétien de Troyes had in his romance Lancelot (c.1180) developed the romantic story of Sir Lancelot and his adulterous affair with Guinevere. Chrétien also introduced Sir Perceval and the quest for the Holy Grail in his Perceval (c.1182), as did Wolfram von Eschenbach in his German epic Parzifal (c.1205).
In the 1220s a further important group of anonymous prose romances appeared in French on the subjects of Lancelot, Merlin, the Holy Grail, and Arthur's death: this body of work, referred to now as the Vulgate Cycle, formed the chief basis for the major English prose version of the legends, Sir Thomas Malory's Le Morte Darthur (completed 1470, published 1485). Malory seems to have drawn also upon two 14th‐century English verse narratives, each titled Morte Arthure, and upon other sources now lost. In the line from Chrétien to Malory, it is notable that Arthur himself, apart from the episodes of his birth, accession, and death, plays little part and is overshadowed by the loves and adventures of Merlin and of the knights Lancelot, Gawain, Tristram, Perceval, Galahad, and others.
These legends have been adapted and retold in various forms and languages over the centuries, the most ambitious version in English being Alfred Tennyson's sequence of verse narratives published intermittently from 1859 and collected as Idylls of the King (1891). See also matter of britain. For a fuller account, consult Derek Pearsall, Arthurian Romance (2003).
http://www.lib.rochester.edu/camelot Camelot Project, archive of Arthurian materials and links.