R. Martin Klein is an American theater, film, and voice actor who went under the alias name Bob Marx in his earlier dubbing work during the 1990s. He is best known for playing Gomamon/Ikkakumon in Digimon: Digital Monsters, Fukurou in Noein and Katsuhiko Jinnai in El Hazard. In addition to voiceovers, Klein has also worked on theater and film productions.