Clarence George Issenmann (May 30, 1907 – July 27, 1982) was an American prelate of the Roman Catholic Church. He served as an auxiliary bishop of the Archdiocese of Cincinnati in Ohio from 1954 to 1957 as bishop of the Diocese of Columbus in Ohio from 1957 to 1964, and as bishop of the Diocese of Cleveland in Ohio from 1966 to 1974.