Locked On is a techno-thriller novel written by Tom Clancy and Mark Greaney released on December 13, 2011. A direct sequel to Dead or Alive (2010), it is Clancy's first of three collaborations with Greaney and features Jack Ryan Jr. and The Campus as they try to avert a nuclear threat from a rogue Pakistani general, as well as his father Jack Sr. in his presidential campaign. The book debuted at number two on the New York Times bestseller list.

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.