Richard Steven Horvitz (born July 29, 1966), sometimes credited as Richard Wood, is an American actor and voice actor. In the world of animation, he has voiced mentally unstable and neurotic characters. He is known for his work voicing the original Alpha 5 in Mighty Morphin Power Rangers, Power Rangers Zeo and Power Rangers Turbo, Raz in Psychonauts, Kaos in Skylanders, Billy and Harold in The Grim Adventures of Billy & Mandy, Grey Matter in Ben 10, Daggett in The Angry Beavers, Bumble in Kinectimals, the titular character in Invader Zim, Orthopox in Destroy All Humans!, the Zoni in Ratchet & Clank and the Space Weaver in Broken Age.