Acclaimed thriller novelist was 66
A staunch Republican and lifelong member of the National Rifle Association, Clancy was revered for his ability to splice technically detailed plotlines with a Cold War thriller narrative.
Born in Baltimore, he worked as an insurance agent while writing his first novel The Hunt for Red October, published in 1984 and described by US President Ronald Reagan as "my kind of yarn".
Six years later it was turned into a movie by director John McTiernan and starred Sean Connery as Soviet submarine captain Captain Marko Ramius and Alec Baldwin as Jack Ryan, a character that would subsequently be played by Harrison Ford and Ben Affleck.
In 1992, Patriot Games was adapted for the big screen with Ford as Ryan, a CIA analyst who becomes the target of the IRA in the form of Sean Bean's relentless Irish terrorist Sean Miller.
Two years later Ford returned to the role in 1994's Clear and Present Danger, in which Ryan becomes embroiled in an illegal war fought by the US government against an illegal Colombian drugs cartel.
In 1998, Clancy's novel Rainbow Six was the basis for a video game, a reworking of his themes that would prove as popular as his movie adaptations, particularly the Splinter Cell series for which he orginated the idea.
Ben Affleck starred in the final adaptation of a Clancy novel - The Sum of All Fears - in 2002 where Ryan must thwart the plans of a terrorist group that threatens to detonate a nuclear weapon at an American football game in Baltimore.
A new Jack Ryan film, Shadow Recruit, directed by Kenneth Branagh and starring Chris Pine, is planned for release later this year.
Clancy died in Baltimore of an unspecified illness.
You can see A Sum of All Fears on Sky Movies.