reference to Aleister Crowley. The Great Beast was the name he signed himself as. 666 is a reference to the number identified with the Antichrist. The Antichrist is a Biblical term often identified with a beast which has 7 heads and 10 horns described in the Old Testament who is supposed to betoken (be a sign of) the end of the world. See also Crowley, Aleister in this glossary.—PDC Volume 4 Approved Glossary