Stockwell Burt Day, Jr., PC, MP (born August 16, 1950 in Barrie, Ontario), is a Canadian politician and a member of the Conservative Party of Canada. He is a former cabinet minister in Alberta, and a former leader of the Canadian Alliance. Day is currently MP for the riding of Okanagan—Coquihalla in British Columbia and the Minister of International Trade. He is widely seen as a prominent voice for social conservatives within the Conservative Party.

Day was born in Barrie, Ontario, in 1950, living in a number of places in Canada during his youth, including Atlantic Canada; Ottawa, where he attended Ashbury College; and Montreal, where he graduated from Westmount High School. He attended the University of Victoria and Vanguard College, then known as Northwest Bible College, in Edmonton, Alberta, but did not graduate from either.

His father, Stockwell Day, Sr., was long associated with the Social Credit Party of Canada. In the 1972 federal election he was the Social Credit candidate running against New Democratic Party leader Tommy Douglas in the riding of Nanaimo—Cowichan—The Islands. Day, Sr., supported Doug Christie and was a member of the Western Canada Concept.