Bob Klein, also known professionally as R. Martin Klein, is an American voice actor with a career spanning from the early 1980s to the present. He began his entertainment career as a drummer before transitioning to acting, making his professional stage debut in the original Broadway production of Annie. After relocating to Los Angeles, he became a prolific voice actor through his work with studios like Saban Entertainment and Animaze.

He is widely recognized for his extensive work in anime, particularly for providing the voice of the Digimon character Gomamon and its evolutions, Ikkakumon and Zudomon, across numerous installments of the Digimon franchise. This includes the original Digimon: Digital Monsters series, the compilation film Digimon: The Movie, and he later reprised the role for the sequel film series Digimon Adventure tri. and the 20th-anniversary film Digimon Adventure: Last Evolution Kizuna. In addition to his long-running role in Digimon, Klein's other notable anime voice roles include Katsuhiko Jinnai in El Hazard, Me-Mania in the film Perfect Blue, Fukurou in Noein, and Flint Hammerhead in Flint the Time Detective. His voice work also extends to popular video games, such as the.hack series, the Dynasty Warriors and Samurai Warriors franchises, and Star Ocean: First Departure.

Beyond anime, Klein has lent his voice to various animated projects, including the series Animalia, the film Lego Star Wars: The Padawan Menace, and the direct-to-video Alpha and Omega film series. Aside from his acting work, he is noted for his advocacy efforts on behalf of kidney patients through his involvement with the Renal Support Network.