Richard Steven Horvitz (born July 29, 1966) is an American actor and voice actor who is best known for doing the voice for Alpha 5 in Mighty Morphin Power Rangers, Power Rangers Zeo, and Power Rangers Turbo, the title character Zim in the Nickelodeon animated series Invader Zim, Billy and his dad Harold in the Cartoon Network animated series The Grim Adventures of Billy & Mandy, Rodney in Squirrel Boy, Razputin Aquato in the video game Psychonauts, Bumble in Kinectimals, Grey Matter in Ben 10, and Daggett Doofus Beaver on the Nickelodeon animated sitcom, The Angry Beavers.

He voiced Ned Frischman in Dave the Barbarian, Aviarius in Kim Possible, a ninja in Fish Hooks, Mouth in Kick Buttowski: Suburban Daredevil, Yucky in Billy Dilley's Super-Duper Subterranean Summer, Scooper in Ted Brooks' crazy dream in Snow Dogs (uncredited), and additional voices in the 1998 Disney animated film, Mulan and in Howl's Moving Castle. He also played Teddy in That's So Raven (episode: "Adventures in Boss-Sitting").