John Patrick Ryan Sr. (Hon.) is a fictional character created by author Tom Clancy and featured in his Ryanverse novels, which have consistently topped the New York Times bestseller list over 30 years. Since Clancy's death in 2013, five other authors, Mark Greaney, Grant Blackwood, Mike Maden, Marc Cameron and Don Bentley, have continued writing new novels for the franchise and its other connecting series with the approval of the Clancy family estate.

Thomas Leo Clancy Jr. was an American novelist. He is best known for his technically detailed espionage and military-science storylines set during and after the Cold War. Seventeen of his novels have been bestsellers and more than 100 million copies of his books have been sold. His name was also used on screenplays written by ghostwriters, nonfiction books on military subjects occasionally with co-authors, and video games. He was a part-owner of his hometown Major League Baseball team, the Baltimore Orioles, and vice-chairman of their community activities and public affairs committees.