Stephen Douglas Thorne (February 11, 1953 – May 24, 1986) was an American Naval officer and a NASA astronaut candidate.  He was born on February 11, 1953, in Frankfurt, Germany, and graduated from the US Naval Academy in 1975. He was a Navy fighter pilot from 1976 until he became a test pilot in 1981.  He was accepted for NASA astronaut training in June 1985, but died in an airplane accident where he was a passenger on May 24, 1986.  He was survived by his wife, Sue. His interests included baseball, running, reading, and general aviation.  He graduated from T.L. Hanna High School, Anderson, South Carolina, in 1971 and received a bachelor of science degree in systems engineering from the U.S. Naval Academy in 1975.

Upon graduation from the Naval Academy, Thorne entered flight training and received his wings in December 1976. Following training in the F-4 Phantom, he joined Fighter Squadron 21 (VF-21) and deployed to the Western Pacific aboard the USS Ranger. After training at the U.S. Naval Test Pilot School in 1981, Thorne spent the next two years at Strike Aircraft Test at the Naval Air Test Center, Patuxent River, Maryland, flying mostly ordnance and weapons systems tests in the F-4 and A-7 Corsair II. He completed F-18 Hornet transition training in October 1984 and joined Strike Fighter Squadron 132 (VFA-132) aboard USS Coral Sea until departing for NASA.  He accumulated over 2,500 hours and 200 carrier landings in approximately 30 different types of aircraft.

Thorne was selected as an astronaut candidate by NASA in June 1985 and in August, commenced a one-year training and evaluation program to qualify him for subsequent assignment as a pilot on future Space Shuttle flights.  Thorne was killed in an aircraft accident of a stunt plane -in which he was a passenger- on May 24, 1986. The stunt plane crashed while performing maneuvers near Santa Fe, Texas, killing Thorne and a NASA engineer.