William M. Sawchuk (born January 8, 1959) is a Canadian former swimmer, competing in the butterfly, freestyle and medley events during the 1970s and early 1980s. In his international debut as a 16-year-old at the 1975 Pan American Games in Mexico City, he won a bronze medal for his third-place finish in the 200-metre individual medley. He represented Canada at the 1976 Summer Olympics in Montreal, Quebec, where he competed in the preliminary heats of the 200 and 400-metre freestyle events, the 400-metre individual medley, and the 4×200-metre freestyle relay.