Richard Steven Horvitz (born July 29, 1966) is an American actor and voice actor who is best known for doing the voice for Billy and his dad Harold in the Cartoon Network animated series The Grim Adventures of Billy & Mandy. He voiced Ned Frischmann in Dave the Barbarian, Aviarius in Kim Possible, a ninja in Fish Hooks, Mouth in Kick Buttowski: Suburban Daredevil, Scooper in Snow Dogs and additional voices in Howl's Moving Castle and in the 1998 Disney animated film Mulan. He also played Teddy in That's So Raven (episode: "Adventures in Boss-Sitting").