Empusa was the shape-shifting demon associated with Hecate and described as having a brass or copper foot.
Greek sources portray Empusa as a supernatural phantom able to change form. She could appear as a woman or as various animals, making her especially difficult to recognize. Her unusual body included one brass, bronze, or copper leg; some accounts instead describe a donkey’s leg or a leg of dung.
Empusa appears memorably in Aristophanes’ comedy The Frogs. While Dionysus travels toward the Underworld, the creature reportedly changes into forms including a bull, a mule, a beautiful woman, and a dog. The scene may be partly a practical joke by Dionysus’s slave, but it preserves important ancient details about the demon.
Empusa was described as sent by Hecate, the goddess associated with crossroads, night, ghosts, and magic. Later writers grouped empusae with lamiai and mormolykeia as predatory female spirits that seduced or fed upon young men. She is not the same creature as a Gorgon or Harpy.