Mark Greaney is an American spy-thriller novelist, best known as Tom Clancy's collaborator on his final books, and for continuing the Jack Ryan character after Clancy's death. He is also known for the "Gray Man" series of novels which are based on the exploits of a CIA operative. Born in Memphis, Tennessee, Greaney previously worked as a waiter and bartender for ten years, then later in a surgical technology company, while working on novels in his spare time. The national success of The Gray Man made him quit his job and make the transition to a full-time writer. Mark has a degree in International Relations and Political Science. In researching The Gray Man series he traveled to ten countries and trained extensively in the use of firearms, battlefield medicine, and close range combative tactics. The rights to The Gray Man are currently owned by Sony Pictures.