In demonology Furcas is a Knight of Hell, and rules twenty legions of demons. He teaches Philosophy, Astronomy (Astrology to some authors), Rhetoric, Logic, Chiromancy and Pyromancy.

Furcas is depicted as a cruel old man with a long beard and hairy head, riding a pale horse.

The etymology of his name seems to be the Latin word 'furca', fork, gallows, claw of a crab.

See also The Lesser Key of Solomon, Ars Goetia.