John William Hepfer (9 February 1924 – 25 April 1997) was a leading missile development engineer who played an important role in the development of the Minuteman and Peacekeeper missiles. During World War II he flew 44 combat missions in the Southwest Pacific Area as a navigator of Consolidated B-24 Liberator bombers. He left the Army after the war but was recalled to active duty during the Korean War. From 1962 to 1965 he worked on the development of aircraft systems at the Air Research and Development Command (ARDC). After working on the design of the McNamara Line at the Defense Communications Agency during the Vietnam War, he was transferred to the Space and Missile Systems Organization (SAMSO) in June 1967, where he worked in the Systems Project Office for the Minuteman missile as the