The writer arrived on best-seller lists in 1984 with The Hunt for Red October. He sold the manuscript to the first publisher he tried, the Naval Institute Press, which had never before bought original fiction.
A string of other hits soon followed, including Patriot Games, Clear and Present Danger, and The Sum of All Fears, which were all made into films, with a fifth based on his CIA hero Jack Ryan set for release later this year.
Clancy said his dream had been simply to publish a book, hopefully a good one, so that he would be in the Library of Congress catalogue.
"We are saddened by the passing of beloved bestselling author Tom Clancy. Fans worldwide, including us, will miss him greatly," publisher Penguin Books USA said on its official Twitter feed.
Born in Baltimore on April 12, 1947, to a postman and his wife, Clancy entered college to study physics, but switched to English saying later that he was not smart enough for the rigours of science. After graduation in 1969, he married his wife Wanda and joined her family's insurance business, all the while putting down ideas for a novel.
In a 1992 interview with The Baltimore Sun, he attributed much of his success to being "lucky," saying that he had a normal middle-class American upbringing. I was a little nerdy but a completely normal kid," Clancy told the paper. "Mom and Dad loved each other. It was like 'Leave it to Beaver."
Clancy died in Johns Hopkins Hospital in his native Baltimore, Maryland.