Larkin married Mary Irwin. She was the daughter of William, a United States Navy commander, and Elizabeth Irwin. One of their sons, Harrison S. Larkin, was a first lieutenant in the United States Air Force and was killed when his plane crashed on April 28, 1950. The Larkin Conference Center at Fort Lee was named for Lieutenant Larkin. Another son, Thomas B. Larkin, Jr., was a lieutenant in the United States Navy. All four Larkins, as well as the Irwins, are buried at Arlington National Cemetery.
