| William Duncan Smith | |
| Office: | Member of the Legislative Assembly of British Columbia |
| Predecessor: | William James Asselstine |
| Successor: | Frank Arthur Calder |
| Term Start: | 1945 |
| Term End: | 1949 |
| Constituency: | Atlin |
| Birth Date: | 4 January 1899 |
| Birth Place: | Edinburgh, Scotland |
| Death Place: | Vancouver, British Columbia |
| Spouse: | Katherine Janet Watson |
| Party: | Coalition |
| Occupation: | Electrician |
| Residence: | Prince Rupert, British Columbia |
William Duncan Smith (January 4, 1899 – April 1, 1977) was a Canadian politician. He served in the Legislative Assembly of British Columbia from 1945 to 1949 from the electoral district of Atlin, a member of the Coalition government.[1] [2]