George Robert Alexander Duncan (25 February 1900 – 11 October 1984) was an Australian rules footballer who played for Carlton in the Victorian Football League, for Stratford in the Gippsland Football League, for Coburg Football Club in the Victorian Football Association, and for Havelock in the Industrial Football League (at the age of 36). Duncan made his debut for Carlton in Round 1 of the 1921 season. He retired from VFL football in 1930, having played 141 senior games for Carlton, and four interstate games for Victoria. He is especially remembered for his performance in "Duncan's match".