In an Arthurian legend in Ulrich von Zatzikhoven's late 12th-century German poem Lanzelet, the loving fairy mistress of Prince Lancelot is named Iblis, an anagram for Sibil/Sybil.
Possibly derived from the Arabic root ب-ل-س (b-l-s) generally meaning "despair, grief" or, alternately, related to the Greek word διάβολος (diabolos) meaning "devil, accuser, slanderer". This is the name given to Satan in Islamic tradition.