EMPUSA , EMPUSAE (pl.)
Greek Mythology
Roman Mythology
In the classical mythology of ancient Greece, EMPUSA was a terrible female supernatural hybrid monster. She was described as having one leg of brass, and the other that of an ass. The EMPUSA was sent by the goddess HECATE to torment and terrify travelers on dark country roads, and they were accused of being the monster that devoured their corpses when terrified to death.
In the folklore of modern Greece she is a shape-shifting evil spirit. She may manifest in the form of an ox, a dog, a mule, or a beautiful woman. She is a frightening SPIRIT to humans but is considered responsible for causing injury to the sheep on the mountains during the noonday heat.
Source: Giants, Monsters, and Dragons: An Encyclopedia of Folklore, Legend, and Myth