Mitch "Muscle Man" Sorrenstein is one of the main characters of Regular Show. He is one of the groundskeepers of the Park. He is a green, strong, and human, who is often seen with his best friend, Hi Five Ghost. Muscle Man made his first debut as a cameo character in the Pilot, and then made an official appearance in Just Set Up the Chairs. Muscle Man is voiced by Sam Marin. His girlfriend is Starla.