Richard Horvitz is an accomplished actor and voice actor. His cartoon credits include Invader Zim (as the voice of Invader Zim), The Grim Adventures of Billy and Mandy (Billy), Angry Beavers (Daggett), Ben 10 (Grey Matter, Sublimino), El Tigre: Adventures of Manny Rivera (Dr. Chipolte Sr., Diego / Dr. Chipolte JR), Code Name: Kids Next Door (Crayon Boy), Dave the Barbarian (Ned), Kim Possible (Aviarius), Mulan, Totally Spies!, Static Shock, Osmosis Jones, Cats & Dogs, Duel Masters, Crash Nebula, Johnny Bravo and Howl's Moving Castle.

His Video Game voice work includes: FusionFall (Billy), Destroy All Humans: Path of the Furon (Orthopox), Nicktoons: Globs of Doom (Invader Zim), Crash: Mind Over Mutant, Ratchet & Clank Future: Quest for Booty (Zoni), Metal Gear Solid 4: Guns of the Patriots (Enemy Soldiers),  Destroy All Humans! (Orthopox / Suburban Crazy), Psychonauts (Raz), Zatch Bell!: Mamodo Battles (Spike/Child), Red Ninja: End of Honor, EverQuest II, Nicktoons: Attack of the Toybots (Invader Zim), Ratchet & Clank Future: Tools of Destruction (Zoni), Crash of the Titans, The Darkness, Destroy All Humans! 2 (Orthopox-13 / The Freak), The Grim Adventures of Billy & Mandy (Billy).

As a screen actor, he can be seen in the 1987 hit Summer School (Alan Eakian), Babylon 5, Kids Incorporated, That's So Raven and Munsters Today. In addition, he is known to Power Ranger fans across the globe as the voice of Alpha 5 in Mighty Morphin' Power Rangers, Power Rangers Turbo, Turbo: A Power Rangers Movie, Power Rangers Zeo, Mighty Morphin Power Rangers: The Movie.