Ralph Leo Hayes (September 21, 1884 – July 5, 1970) was an American prelate of the Roman Catholic Church. He served as the fourth bishop of the Diocese of Helena in Montana from 1933 to 1935, and as the fifth bishop of the Diocese of Davenport in Iowa from 1944 to 1966. Between his two episcopal appointments, Hayes served as the rector of the Pontifical North American College in Rome from 1935 to 1944.