Jay Waldo Monteith, PC (June 24, 1903 – December 19, 1981) was a Canadian politician.

Born in Stratford, Ontario, the son of Joseph Dunsmore Monteith, an Ontario MPP and cabinet minister, and Allice Chowen, he graduated from the University of Toronto and became a chartered accountant in 1932.

He was first elected to the House of Commons of Canada in 1953 as a Progressive Conservative Member of Parliament for the riding of Perth, Ontario.

He famously remarked to Lester Pearson that 'you must be nuts!'

after Pearson presumed to ask Tories to give up their fight to keep Canada's Red Ensign.