In demonology, Furcas (also spelled Forcas) is a Knight of Hell (the rank of Knight is unique to him), and rules 20 legions of demons.^[1][2] He teaches Philosophy, Astronomy (Astrology to some authors), Rhetoric, Logic, Chiromancy and Pyromancy.

Furcas (also known as Ren Vacca) is depicted as a strong old man with white hair and a long white beard, who rides a horse while holding a sharp weapon (pitch fork).

Furcas is a knight and commeth foorth in the similitude of a cruell man, with a long beard and a hoarie head, he sitteth on a pale horse, carrieng in his hand a sharpe weapon, he perfectlie teacheth practike philosophie, rhetorike, logike, astronomie, chiromancie, pyromancie, and their parts: there obeie him twentie legions.

— Johann Weyer (1583)^[3]

Notably, attributes of Furcas seem to slightly vary between the 1563 and 1583 publications of Pseudomonarchia Daemonum. According to a translation by Joseph H. Peterson:

Foras [*Forras], alias Forcas is a great president, and is seene in the forme of a strong man, and in humane shape, he understandeth the vertue of hearbs and pretious stones: he teacheth fullie logicke, ethicke, and their parts: he maketh a man invisible, wittie, eloquent, and to live long; he recovereth things lost, and discovereth [discloses] treasures, and is lord over nine and twentie legions.

— Johann Weyer (1563)^[4][5]

The etymology of his name may be derived from the Latin word furca, meaning fork,^[6] or from Greco-Roman also meaning a sepulchre (tomb).^[7]