Baphomet

A fabulous creature the precise form of which has been the subject more of speculation than fact.  It is variously described as

1. a manifestation of the Devil in the form of a seated winged hermaphrodite, with the body of a goat-headed and goat-footed man, a torch on his head, bearing women's breasts and a caduceus arising from his groin;
2. a pentacle enclosing a goat's head with other symbols;
3. a creature having two heads, male and female, the rest of the body female;
4. the decapitated head of a Sufi martyr of the 19th century.

Not strictly a heraldic device in itself, the last is included as a matter of interest because of its association as a symbol with the Knights Templar.

See Monsters and Mythical Creatures