Beirne Lay Jr. was an American writer, aviation writer, Hollywood screenwriter, and combat veteran of World War II with the U.S. Army Air Forces. He is best known for his collaboration with Sy Bartlett in authoring the novel Twelve O'Clock High and adapting it into a major film.

Twelve O'Clock High is a 1949 American war film directed by Henry King and based on the novel of the same name by Sy Bartlett and Beirne Lay, Jr. It stars Gregory Peck as Brig. General Frank Savage. Hugh Marlowe, Gary Merrill, Millard Mitchell, and Dean Jagger also appear in supporting roles.