Charles James Mayer, PC (born April 21, 1936) is a Canadian businessman and former federal Minister of Agriculture. He was educated at the University of Saskatchewan and became an agrologist and farmer. Politically active, Mayer was president of the Manitoba Beef Growers Association before entering the House of Commons of Canada as a Progressive Conservative Member of Parliament in 1979. He represented the Manitoba riding of Portage—Marquette (later Lisgar—Marquette) until his defeat in 1993.