Robert Martin Klein is an American voice actor with a career spanning several decades, beginning in the early 1980s. He is known for his extensive work in anime dubbing, often credited under various pseudonyms including Bob Marx, Bill Lader, and Bob Klein. Based in Los Angeles, he entered the dubbing industry around 1995 and has built a reputation for his flexible vocal range, allowing him to portray a wide variety of characters.

Klein has contributed voices to numerous anime series and films. One of his most prominent and long-running roles is Gomamon and its evolutions in the Digimon franchise, a character he has voiced across multiple series including Digimon: Digital Monsters, Digimon Adventure tri., and the film Digimon Adventure: Last Evolution Kizuna. He is also recognized for playing the antagonist Katsuhiko Jinnai in the El Hazard series, Fukurou in Noein, and the obsessive fan Me-Mania in the film Perfect Blue. In the series Magical Meow Meow Taruto, he provided the voice for the character Kakipi.

His filmography includes other notable roles such as Marumaro in Blue Dragon, Ivan Whisky/Cyborg 001 in Cyborg 009, Jidan Nickard in Mobile Suit Gundam: The 08th MS Team, and Flint Hammerhead in Flint the Time Detective. He has also voiced characters in FLCL, Zatch Bell!, and Hand Maid May, among many others.

Beyond animation, Klein's voice can be heard in numerous video games. His work includes roles in the.hack series as Harald Hoerwick and Marlo, Hideyoshi Toyotomi in the Warriors Orochi series, Lias Warren in Star Ocean: First Departure, and Mugetsu in The Bouncer. He frequently used the alias Bob Marx for non-union projects in the 1990s and has also been credited as Bill Lader. A notable achievement in his career is his sustained association with the Digimon franchise, voicing the beloved character Gomamon across various productions for over two decades.