A knight who was challenged by Arthur for ownership of the Black Forest.
The Black Knight logically contended that since his name was the “Black Knight of the Black Forest”, the Black Forest must be his. To win his claim, the Black Knight had to defeat all of Arthur’s knights. He came close, but was defeated by Sir Meriadoc.
The noble Meriadoc, however, convinced Arthur to return the Black Forest to the Black Knight.
Source
Historia Meriadoci Regis Cambrie | Late 13th century