Derfel Cadarn ("Derfel the Mighty") is a fictional character and the protagonist in The Warlord Chronicles by Bernard Cornwell. He is a straightforward and gifted warrior who is loyal and trustworthy. He is a highly fictionalized version of Saint Derfel Gadarn of Wales and of Sir Bedivere. Derfel is one of Arthur's closest advisers and friends, is one-handed (in Welsh legends) and in many versions of the legends, casts Excalibur into the sea after the Battle of Camlann.