Mark Greaney, who co-wrote Tom Clancy’s final Jack Ryan novels, is also the author of "The Gray Man" series. In his new ...

Is 'The Gray Man' based on a book? Yes, "The Gray Man" is based on a series of novels by Mark Greaney. The books follow Six, a.k.a. Court Gentry, a freelance assassin and former CIA mercenary.

Based on Mark Greaney’s 2009 novel of the same name, The Gray Man centers around CIA Agent “Sierra Six” (Gosling) who is on the run from a sociopathic ex-CIA agent and mercenary Lloyd Hansen ...