Lucan the Butler is a servant of King Arthur and the son of Duke Corneus, brother to Bedivere and cousin to Griflet. He and his relatives are among Arthur's earliest allies in the fight against the rebel kings such as Lot, Urien and Caradoc, and remained one of Arthur's loyal companions throughout his life.
Lucan was a solid and reliable Knight of the Round Table and one of King Arthur's earliest companions. He took on the post of royal butler – an important position in charge of the royal household rather than a serving man. The duties of a "butler" have changed over time; Lucan was supposed to have been in charge of the royal court, along with Bedivere the Marshal and Kay the Seneschal. He valiantly defended Arthur's right to the throne at the Battle of Bedegraine and against subsequent rebellions. Though he sought adventure, he never came to the fore in Arthurian tales with renowned exploits of his own. He always attended the royal tournaments and was once hurt so badly by Tristram that Yvain had to escort him to Gannes Abbey for medical assistance.
In most accounts of Arthur's death, from the Lancelot-Grail cycle to Le Morte d'Arthur, Lucan is one of the last knights at the king's side at the Battle of Camlann and is usually the last of them to die. Lucan remained loyal to King Arthur throughout the schism with Lancelot and on occasion acted as their go-between. Similarly, he stayed by the monarch's side during Mordred's rebellion and tried to dissuade Arthur from his final attack on his son/nephew, but was unsuccessful and the King received his mortal wound. Himself gravely wounded himself, Lucan was one of the few knights left at Camlann, along his brother, Bedivere. Worried about looters on the battlefield, Lucan and Bedivere attempts to move the dying Arthur into a nearby chapel for safety, but the strain is too much for Lucan as a severe wound bursts open, spilling out his bowels; he dies from his own wounds just before the king returns Excalibur to the Lady of the Lake and sails off for Avalon. Though the knight Arthur asks to cast the sword into the lake is usually Griflet (Lancelot-Grail) or Bedivere (Le Morte d'Arthur, the Alliterative Morte Arthure, the Stanzaic Morte Arthur), the 16th-century English ballad King Arthur's Death ascribes this duty to Lucan.
In modern works, a character named Lucan appears in the 2004 film King Arthur, played by Johnny Brennan. He is a young boy found and cared for by Arthur's warrior Dagonet.