Douglas "Dally" Duncan (14 October 1909 – 2 January 1990) was an Aberdeen-born football player and manager.
A left-winger, Duncan joined Hull City from Aberdeen Richmond in 1928 and spent his entire professional career in England. He joined Derby County for £2,000 in 1932 and remained contracted to the club until 1946. During this period he earned 14 caps for the Scottish national team, scoring 7 goals between 1932 and 1937. He was also received an FA Cup winners medal with Derby in 1946.