Tom Clancy was born at Franklin Square Hospital in Baltimore, Maryland, on April 12, 1947, and grew up in the Northwood neighborhood. He was the second of three children to Thomas Clancy, who worked for the United States Postal Service, and Catherine Clancy, who worked in a store’s credit department. His mother worked in order to send him to the private Catholic Loyola Blakefield in Towson, Maryland, from which he graduated in 1965. He then attended Loyola College (now Loyola University) in Baltimore, graduating in 1969 with a degree in English literature. While at university, he was president of the chess club. He joined the Army Reserve Officers’ Training Corps; however he was ineligible to serve due to his nearsightedness, which required him to wear thick eyeglasses. After graduating he worked for an insurance company in Hartford, Connecticut. In 1973, he joined the O. F. Bowen Agency, a small insurance agency based in Owings, Maryland, founded by his wife’s grandfather. In 1980, he purchased the insurance agency from his wife’s grandmother, and wrote novels in his spare time. While working at the insurance agency, he wrote The Hunt For Red October.

Clancy’s literary career began in 1982 when he started writing The Hunt for Red October which in 1984 he sold for publishing to the Naval Institute Press for $5,000. The publisher was impressed with the work; Deborah Grosvenor, the Naval Institute Press editor who read through the work, said later that she convinced the publisher: “I think we have a potential best seller here, and if we don’t grab this thing, somebody else would,” and considered that Clancy had an “innate storytelling ability, and his characters had this very witty dialogue”. The publisher requested Clancy to cut numerous technical details, amounting to about 100 pages. Clancy, who had wanted to sell 5,000 copies, ended up selling over 45,000. After publication, the book received praise from President Ronald Reagan, calling the work “the best yarn”, subsequently boosting sales to 300,000 hardcover and 2 million paperback copies of the book, making it a national bestseller. The book was critically praised for its technical accuracy, which led to Clancy’s meeting several high-ranking officers in the U.S. military.

Clancy’s fiction works, The Hunt for Red October (1984), Patriot Games (1987), Clear and Present Danger (1989), and The Sum of All Fears (1991), have been turned into commercially successful films with actors Alec Baldwin, Harrison Ford, and Ben Affleck as Clancy’s most famous fictional character Jack Ryan, while his second most famous character, John Clark, has been played by actors Willem Dafoe and Liev Schreiber. All but two of Clancy’s solely written novels feature Jack Ryan or John Clark.

The Cold War epic Red Storm Rising, co-written (according to Clancy himself in the books foreword) with fellow military-oriented author Larry Bond, was published in 1986.  The first NetForce novel (titled Net Force and published in 1999) was adapted as a 1999 TV movie starring Scott Bakula and Joanna Going. The first Op-Center novel was released to coincide with a 1995 NBC television mini-series of the same name (Tom Clancy’s Op-Center published in 1995) starring Harry Hamlin and a cast of stars. Though the mini-series did not continue, the book series did, but it had little in common with the first mini-series other than the title and the names of the main characters.

With the release of The Teeth of the Tiger (2003), Clancy introduced Jack Ryan’s son and two nephews as main characters; these characters continued in his last four novels, Dead or Alive (2010), Locked On (2011), Threat Vector (2012), and Command Authority (2013).  Clancy wrote several nonfiction books about various branches of the U.S. Armed Forces (see non-fiction listing, below). Clancy also branded several lines of books and video games with his name that are written by other authors, following premises or storylines generally in keeping with Clancy’s works. These are sometimes referred to by fans as “apostrophe” books; Clancy did not initially acknowledge that these series were being authored by others; he only thanked the actual authors in the headnotes for their “invaluable contribution to the manuscript”.

By 1988, Clancy had earned $1.3 million for The Hunt for Red October and had signed a $3 million contract for his next three books. By 1997, it was reported that Penguin Putnam Inc. (part of Pearson Education) would pay Clancy $50 million for world rights to two new books, and another $25 million to Red Storm Entertainment for a four-year book/multimedia deal. Clancy followed this up with an agreement with Penguin’s Berkley Books for 24 paperbacks to tie in with the ABC television miniseries Tom Clancy’s Net Force aired in the fall/winter of 1998. The Op-Center universe has laid the ground for the series of books written by Jeff Rovin, which was in an agreement worth $22 million, bringing the total value of the package to $97 million.

In 1993, Clancy joined a group of investors that included Peter Angelos and bought the Baltimore Orioles from Eli Jacobs. In 1998, he reached an agreement to purchase the Minnesota Vikings but had to abandon the deal because of a divorce settlement cost.  In 2008, the French video game manufacturer Ubisoft purchased the use of Clancy’s name for an undisclosed sum. It has been used in conjunction with video games and related products such as movies and books. Based on his interest in private spaceflight and his US$1 million investment in the launch vehicle company Rotary Rocket, Clancy was interviewed in 2007 for the documentary film Orphans of Apollo (2008).  Clancy and his first wife Wanda Thomas King, a nursing student who became an eye surgeon, married in 1969, separated briefly in 1995, and permanently separated in December 1996. Clancy filed for divorce in November 1997, which became final in January 1999.

On June 26, 1999, Clancy married freelance journalist Alexandra Marie Llewellyn, whom he had met in 1997. Llewellyn is the daughter of J. Bruce Llewellyn and a family friend of Colin Powell, who originally introduced the couple to each other. They remained together until Clancy’s death in October 2013.  Clancy’s estate, which was once a summer camp, is located in Calvert County, Maryland. It is 80 acres (32 ha) and has a panoramic view of the Chesapeake Bay. The stone mansion, which cost US$2 million, has twenty-four rooms and features a shooting range in the basement. The property also features a World War II-era M4 Sherman tank, a Christmas gift from his first wife.  Clancy also purchased a 17,000 square feet (1,600 m2) penthouse condominium in the Ritz-Carlton in Baltimore’s Inner Harbor for US$16 million.

Clancy died on October 1, 2013, of an undisclosed illness at Johns Hopkins Hospital, near his Baltimore home. Clancy is survived by his wife, Alexandra; their daughter, Alexis; and four children from his marriage to Wanda King: Michelle Bandy, Christine Blocksidge, Kathleen Clancy, and Thomas Clancy III. The Chicago Tribune quoted Pulitzer Prize-winning author Stephen Hunter as saying, “When he published The Hunt for Red October he redefined and expanded the genre and as a consequence of that, a lot of people were able to publish such books who had previously been unable to do so.”  John D. Gresham, a co-author and researcher with Clancy on several books, attributed Clancy’s death to heart problems: “Five or six years ago Tom suffered a heart attack and he went through bypass surgery. It wasn’t that he had another heart attack, [his heart] just wore out.”