"The Gray Man" is a thriller novel written by Mark Greaney, featuring the character Court Gentry, a skilled assassin known as the Gray Man. The story follows Gentry as he navigates a dangerous world of espionage and betrayal, where he is pursued by various enemies due to his lethal skills and past actions. The novel is the first in a series that combines action, suspense, and intricate plotting. It explores themes of morality and survival, as Gentry must use his intelligence and combat abilities to stay alive while uncovering deeper conspiracies that threaten his life and those around him.