Ruth J. Coster (1918-2005) of Bonsal, North Carolina, served in the United States Army Air Corps while a member of the Women's Army Corps (WAC) from March 1944 to January 1946.

Ruth L. Johnson Coster was born 11 December 1918, in Bonsal, North Carolina. She graduated from Bahama High School outside of Durham, NC, in 1937 and went to work for the tobacco company Lucky Strike. One or two years later, she moved to Sanford, North Carolina, to work at her sister's service station.

In March 1944, Coster joined the WAC so she could work in the Army Air Corps. She had basic training at Fort Oglethorpe in Georgia and was then stationed at McClellan Field in Sacramento, California, for a few months. Coster returned to Fort Oglethorpe in the fall for overseas training, and on 18 November 1944 she sailed from Camp Stoneman, California, to New Guinea on the United StatesS Monterey. In New Guinea, she was stationed in the supply office of the Far East Air Service Command (FEASC). In August 1945, the FEASC moved to Manila, Philippines, and Coster became a WAC supervisor.

She returned to the United States in December and was discharged 1 January 1946. Coster returned to McClellan Air Force Base to work as a civilian, and soon met Don Coster. They married in December 1947 and lived in Sacramento with their three daughters. Ruth Coster died 8 August 2005.