Thomas Coltrin Keefer CMG (4 November 1821 – 7 January 1915) was a Canadian civil engineer.

Born into a United Empire Loyalist family in Thorold Township, Upper Canada, the son of George Keefer and Jane Emory, née McBride, his father was chairman of the Welland Canal Company.

He became well known for his writings, particularly Philosophy of Railroads and The Canals of Canada: Their Prospects and Influence, and surveyed a railway connecting Kingston, Ontario, and Toronto (1851), was in charge of the survey for a line between Montreal and Kingston, and determined the site for the Victoria Bridge that crosses the St. Lawrence River into Montreal.

He served as chief engineer of the Montreal Water Board and designed the water-supply system for Hamilton, Ontario (1859), as well as the waterworks in Ottawa (1874).

His Hamilton pumping station, with its working Gartshore beam engines, has been declared a national historic site.