Empousa or Empusa was a female spirit in Greek mythology. The origin of the figure is unclear. Her mother was probably Hectate. Empousa seems to have been a spirit used to frighten people. In appearance, she probably resembled Mormo and Lamia. She seems to have had the abilty to change her appearance or shape (know as shapeshifting).
One of the first t describe her was the Ancient Greek poet Aristophanes, in his comedy The Frogs: When the Greek god Dionisus is on the way to the underworld with his slave Xanthias, Empusa appears in different forms (animals: cow, donkey, dog), and finally as a woman. One of her legs is made of iron, the other is made of cow dung.