| James Dempsey | |
| Office: | Ontario MPP |
| Term Start: | 1945 |
| Term End: | 1955 |
| Predecessor: | Thomas Patrick Murray |
| Successor: | James Maloney |
| Constituency: | Renfrew South |
| Party: | Progressive Conservative |
| Birth Date: | 9 February 1887 |
| Birth Place: | Calabogie, Ontario |
| Death Place: | Toronto, Ontario |
| Occupation: | Contractor, lumberman |
James Shannon Dempsey (February 9, 1887 – October 24, 1955) was a Canadian politician who was a Member of Provincial Parliament in Legislative Assembly of Ontario from 1945 to 1955. He represented the riding of Renfrew South for the Ontario Progressive Conservative Party.
He was born in Calabogie, Ontario and was a contractor and lumberman.[1] He died in office of a heart attack in 1955.[2]