Marty Klein was born in Montreal, Canada and raised in Colorado, USA. He worked as a disc jockey, a stand-up comic, and as road manager for comedian Shelly Berman. He became a talent agent in 1964 and four years later joined the Agency for the Performing Arts (APA). He was a major talent agent and president of the Agency for the Performing Arts between 1977-92.
He nurtured the careers of many prominent comedy performers. Klein's illustrious list of clients included Al Pacino, Steve Martin, Martin Mull, David Letterman, John Candy, Rodney Dangerfield, Sam Kinison, Rowan & Martin and country & western legend Johnny Cash.