Best Selling Author Tom Clancy Has Died The "Patriot Games" writer was 66 years old.

Oct. 2, 2013 -- Tom Clancy, a prolific writer famous for his best sellers about espionage and the military, died Oct. 1 at the age of 66, ABC News has confirmed with his publisher, Penguin Group.

The cause of death is unknown.

"I'm deeply saddened by Tom's passing. He was a consummate author, creating the modern-day thriller, and was one of the most visionary storytellers of our time," Penguin Group executive David Shanks said in a statement. "I will miss him dearly and he will be missed by tens of millions of readers worldwide."

Clancy, a Baltimore native who joined R.O.T.C. in college but had to drop out because of his poor eyesight, worked at an insurance agency before turning his passion -- writing -- into a full-time job. He published his first book, "The Hunt for Red October," in 1984. The novel was later turned into a film, starring Alec Baldwin and Sean Connery. Several of Clancy's books were turned into movies.

According to Clancy, this was the job he was always meant to do.

In Memoriam Photos: Tom Clancy

As a child, ''I never read kids' books,'' he told New York Times magazine in 1988. ''At least not the usual kids' books. I remember reading Jules Verne in the third grade. I started on Samuel Eliot Morrison in the fourth or fifth grade - he started me on military history. I read a lot of science fiction. I read every genre you can imagine.''

It was a lucrative passion. According to the profile, Clancy earned $1.3 million for his first book, and inked a $3 million contract for the next three, ''Red Storm Rising," ''Patriot Games'' and ''The Cardinal of the Kremlin."

He would go on to write many other novels, including "Clear and Present Danger" and "The Sum of All Fears." His final book, "Command Authority," is due out in December.

In 1996, he co-founded Red Storm Entertainment, which developed video games based on his military expertise.

Clancy leaves behind four children from his first marriage and a wife, Alexandra Marie Llewellyn, whom he married in 1999.