A demonic lord encountered by Gawaine and Perceval in Perlesvaus. He ruled a hellish castle in the Wild Forest, from which he robbed women. One of his victims was the enigmatic Maiden of the Cart, from whom he stole the heads of 152 knights.
Gawaine learned that the Black Hermit was an earthly manifestation of Lucifer, and that only Perceval could defeat him. At the urging of the Maiden of the Cart, Perceval traveled to the Black Hermit’s castle and defeated him in a joust. Seeing their lord fallen, the Black Hermit’s own knights threw him into a chasm of filth.
Source
Perlesvaus | Early 13th century