The cause of death or the nature of his illness has not been disclosed. Clancy went from an insurance salesman to a best selling author in 1984 after his debut novel, "The Hunt For Red October," became a best seller and even received a ringing endorsement from then President Ronald Reagan who called the book his "kind of yarn" and enthused that he couldn't put it down.

That book started a hit series of books centered on the Jack Ryan character that also spawned a series of hit movies starring Harrison Ford, Alec Baldwin and Ben Affleck as the title character.

17 of Clancy's books have topped the New York Times's best-seller list, including his most recent novel, "Threat Vector," which was released in December of last year.

The next book in the Jack Ryan series, "Command Authority," which Clancy co-wrote with his frequent collaborator Mark Greaney, is scheduled to be published on December 3rd.