Stephen Reginald Bosustow (November 6, 1911 in Victoria, British Columbia – July 4, 1981) was a Canadian-born American film producer from 1943 until his retirement in 1979. He was one of the founders of United Productions of America (UPA) and produced nearly 600 cartoon and live-action shorts. He is chiefly remembered for producing a string of Mr. Magoo and Gerald McBoing-Boing cartoons in the 1950s, two of which earned Academy Awards.