 Grover Underwood is a satyr and Percy's best friend.He appears in "The Lightning Thief, The Sea of Monsters, The Titan's Curse, The Battle of the Labyrinth, The Last Olympian, The Son of Neptune, The House of Hades, The Blood of Olympus" and "The Burning Maze".He has curly reddish-brown hair and fur, acne, and a wispy goatee.