Grover Underwood is a fictional character in Rick Riordan's "Percy Jackson and the Olympians" series. He is a satyr, a mythological Greek being that is half goat and half human. He has the upper body of a human and the legs and horns of a goat. He uses fake feet when he wants to look like a human. His horns are usually hidden by his curly brown hair (although they do eventually grow too tall for him to hide them) and sometimes an orange rasta cap. Although he is 32 years old, he is like a sixteen year-old human because satyrs age half as fast as humans do.