Chalmers Jack Mackenzie, CC CMG MC FRS FRSC[1] (July 10, 1888 – February 26, 1984) was a Canadian civil engineer, chancellor of Carleton University, president of the National Research Council, first president of Atomic Energy of Canada Limited, first president of Atomic Energy Control Board and instrumental in the development of science and engineering education in Canada.

He was born in St. Stephen, New Brunswick, the youngest of six children of James and Janet MacKenzie.

After the war he continued at the University of Saskatchewan until 1932, when he took a leave of absence to supervise public works projects.

In 1939 he left Saskatchewan for Ottawa to become president of the National Research Council.

In 1949 he sat on the Royal Commission on National Development in the Arts, Letters and Sciences, the so-called "Massey Commission", one objective of which was developing Canada's system of publicly funded research.