Richard Steven Horvitz, also known as Richard Wood (born July 29, 1966), is an American actor, comedian, singer, musician and voice actor. In the world of animation, he voiced neurotic and mentally unstable characters. He is known for his work as the voice of the original Alpha 5 in Mighty Morphin Power Rangers, Power Rangers Zeo, and Power Rangers Turbo, Razputin in Psychonauts, Kaos in the Skylanders franchise, Billy and his dad Harold in The Grim Adventures of Billy & Mandy,Grey Matter in Ben 10, Daggett in The Angry Beavers, Bumble in Kinectimals, the title character Zim in Invader Zim,Mouth in Kick Buttowski, Orthopox in the Destroy All Humans! series, Telapathopus Brain Scientist in Ratchet & Clankand the Space Weaver in Broken Age.
- Crossover Universe - Billy, Harold, Chaz, Joey, Mr. Spokes
- Multiverse X - Billy, Harold, Chaz, Joey, Mr. Spokes
- House of Animals (TV Series) - Billy, Harold
- The Secret Life of Mandy Hillson - Billy, Harold
- Teen Titans (Alternate Season 2) - Mister Mind
- Miscellanous! Cartoons - Gilbert the Chihuahua, additional voices