Robert Martin Klein, frequently credited as R. Martin Klein or by the alias Robert Kline, is an American voice actor with a career spanning several decades in the animation and video game industries. He was born on May 11, 1957, and is based in Los Angeles. Throughout his career, he has worked under various pseudonyms, including Bob Marx for earlier dubbing work in the 1990s, as well as Bill Lader and Bob Klein for non-union projects.

Klein is known for his flexible vocal range, which has allowed him to portray a wide variety of characters in English adaptations of Japanese anime. His most prolific and enduring role is that of Gomamon and its evolutions, including Ikkakumon, in the Digimon franchise. He first voiced the character in Digimon: Digital Monsters and has reprised the role numerous times across subsequent series, films, and video games for over two decades, including Digimon Adventure tri. and Digimon Adventure: Last Evolution Kizuna.

Beyond Digimon, Klein's filmography includes a broad array of prominent roles in English-dubbed anime. He is recognized for his work as Katsuhiko Jinnai in El Hazard, Ivan Whisky/Cyborg 001 in Cyborg 009, Fukurou in Noein, and Mr. Me-Mania in the cult classic film Perfect Blue. He also voiced Solaris in the Gatchaman OVA series. His credits extend to other popular series such as FLCL, Mobile Suit Gundam: The 08th MS Team, and Zatch Bell!.

In addition to his extensive anime work, Klein has contributed voices to numerous video games. Notable credits include Marumaro in Blue Dragon, Mugetsu in The Bouncer, Hideyoshi Toyotomi in the Warriors Orochi series, and multiple characters in the.hack franchise. His work also encompasses non-anime animated productions, such as providing voices for the LeapFrog educational DVDs and playing Chancellor Palpatine in Lego Star Wars: The Padawan Menace.