Duncan Macmillan (February 11, 1837 – April 21, 1903) was a Canadian lawyer, judge and political figure in Ontario, Canada.
He represented Middlesex East in the House of Commons of Canada from 1875 to 1887 as a Liberal-Conservative member.
[1] He was born in London Township, Upper Canada,[1] the son of William Macmillan, and was educated at Queen's University.
Macmillan studied law with Sir John A. Macdonald and was called to the bar in 1861.
[3] He was elected to the House of Commons in an 1875 by-election held after Crowell Willson was unseated.