A demonic lord who, in Perlesvaus, inhabited the Castle of Giants on the Island of the Elephants.
The Knight carried a shield which was possessed by a devil, and which spouted bursts of flame on command. He terrorized Arthur’s lands, and crispened many good knights, including Perceval’s cousin Alain. Perceval sought to avenge the deed. Protected by his own magic shield, Perceval journeyed to the Knight’s castle and defeated him in combat. The Knight’s shield turned on its master and blasted him to cinders.
A similar character is called the Knight of the Dragon in the Fourth Continuation of Chrétien’s Perceval.
Source
Perlesvaus | Early 13th century