Robert Gray was born on May 24, 1919, in Killeen, Texas. He enlisted in the Aviation Cadet Program of the U.S. Army Air Corps on June 29, 1940, and was commissioned a 2d Lt and awarded his pilot wings at Randolph Field, Texas, on February 8, 1941. His first assignment was as a B-25 Mitchell pilot with the 34th and then the 95th Bomb Squadron of the 17th Bomb Group at McChord Field, Washington, from February 1941 until he was selected for the Doolittle Mission in February 1942. Lt Gray served as the pilot on the 3rd B-25 to take off from the aircraft carrier USS Hornet (CV-8) on April 18, 1942, and after bombing targets in Tokyo, the crew flew to China and bailed out when their aircraft ran out of fuel. After the raid and evading capture, he remained in the China-Burma-India Theater and served as a B-25 pilot with the 11th Bomb Squadron of the 7th and then 341st Bomb Group in India until he was killed in action during a combat mission near Assam, India, on October 18, 1942. Capt Gray was originally buried at Barrackpore, India, but his remains were returned to the United States in February 1951, and reinterred at the Killeen City Cemetery in Killeen, Texas.

His Distinguished Flying Cross Citation reads:

For extraordinary achievement while participating in a highly destructive raid on the Japanese mainland on April 18, 1942. Lieutenant Gray volunteered for this mission knowing full well that the chances of survival were extremely remote, and executed his part in in with great skill and daring. This achievement reflects high credit on Lieutenant Gray and the military service.