G.G. Heffelfinger was a Presbyterian and later United Church minister, whose Saskatchewan pastorates included Buchanan, Grenfell, Vanscoy, Melfort, Sixth Avenue United Church (Regina), and Watrous.

Born in Nebraska, Heffelfinger and his family moved to Drinkwater, Saskatchewan, in 1907. He attended the University of Saskatchewan, receiving his Bachelor of Arts degree in 1916. During the First World War, he served as a stretcher-bearer with the Canadian Medical Corps (12th Field Ambulance) overseas, and was awarded the Military Medal. After the war, Heffelfinger pursued theological training, at New College (Edinburgh) and St. Andrew's College (Saskatoon), and was ordained by the Presbyterian Church, in 1921. He married Jean Watkins, in 1922.

Heffelfinger served as minister in Buchanan, Saskatchewan, 1921–1924, and Fort William, Ontario, 1924–1929. He received his Bachelor of Divinity degree from United College (Winnipeg). Returning to Saskatchewan, he served in Grenfell, 1929–1933, Vanscoy, 1933–1934, Melfort, 1934–1936, and Oxbow, 1937–1942. After receiving a Bachelor of Education degree, he became Saskatchewan director for the Canadian Legion Educational Services.

After the Second World War, Heffelfinger served as minister at Sixth Avenue (later called St. John's) United Church, in Regina, 1946–1956, then at Atwood and Springfield (London Conference), in Ontario, until he retired, in 1962. Returning to Saskatchewan, he came out of retirement to serve as minister to Watrous, where he remained from 1962–1964.