Leonard is a demon or spirit, grand master of the sabbaths, chief of the subaltern demons, and inspector general of sorcery, black magic and witchcraft. He is represented as a three-horned goat, with a black human face. He marks his initiates with one of his horns. Infernal powers obtained from the worship of Master Leonard range from metamorphosis into monstrous animals or men to flight as an Incubus.
There is mention of a "Master Leonard" in the Dictionary of Phrase and Fable in association with the alleged deity of the Templars, Baphomet or "Goat of Mendes." Black banquets are thrown in Leonard's honor where aborted kid goats are eaten without salt and boiled with reptiles to sully the sinless nature of the clean meat.
Leonard has been known to take other forms, and there is some connection to the legend of the werewolf; he has been known to appear as a handsome soldier, a favorite of many demons. In this form he will seduce a young lady and take her to the wilderness where he will lay with her and later impregnate her. Any child resulting from this union will be stillborn, an offering for sin.