Wikipedia
Fierabras
Fierabras (from French: fier à bras, "brave/formidable arm") or Ferumbras is a fictional Saracen knight (sometimes of gigantic stature) appearing in several chansons de geste and other material relating to the Matter of France. He is the son of Balan, king of Spain, and is frequently shown in conflict with Roland and the Twelve Peers, especially Oliver, whose prowess he almost rivals. Fierabras eventually converts to Christianity and fights for Charlemagne.