| Duncan MacMillan | |
| Birth Date: | 27 August 1887 |
| Death Place: | Edmonton, Alberta, Canada |
| Birth Place: | Norland, Ontario, Canada |
| Office: | Member of the Legislative Assembly of Alberta |
| Constituency: | Lacombe |
| Term Start: | 1935 |
| Term End: | 1952 |
| Predecessor: | Irene Parlby |
| Successor: | Allen Russell Patrick |
| Party: | Social Credit |
Duncan Bruce MacMillan (August 27, 1887 - December 20, 1962) was a provincial politician from Alberta, Canada. He served as a member of the Legislative Assembly of Alberta from 1935 to 1952, sitting with the Social Credit caucus in government.[1] [2]