List of Percy Jackson and the Olympians characters
Medusa: The gorgon monster who, under the moniker of "Aunty Em", attempted to lull Percy, Annabeth, and Grover into a false sense of security and turn them into stone statues. She is defeated, and her severed head is mailed to the gods of Olympus as proof of the trio's courage (though Grover notes that it is more akin to impertinence). Percy's mom uses her head to turn Gabe Ugliano to stone.