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.

The movie, set up at Netflix by filmmaker duo Anthony and Joe Russo, is based on Mark Greaney's 2009 novel ... have been kept under wraps. "The Gray Man" will also feature actor Ana de Armas ...