What is "geryon"

In Greek mythology, Geryon ( or ; also Geryone; , genitive: Γηρυόνος), son of Chrysaor and Callirrhoe and grandson of Medusa, was a fearsome giant who dwelt on the island Erytheia of the mythic Hesperides in the far west of the Mediterranean. A more literal-minded later generation of Greeks associated the region with Tartessos in southern Iberia. Geryon was often described as a monster with human faces.

In the Dungeons & Dragons role-playing game, Geryon was an Arch-Devil of Hell ( Baator in later editions of the game), also known as the "Wild Beast."