| Duncan Alexander Ross | |
| Office1: | Ontario MPP |
| Term Start1: | 1919 |
| Term End1: | 1923 |
| Predecessor1: | Hugh Munro |
| Successor1: | James Alexander Sangster |
| Constituency1: | Glengarry |
| Party: | United Farmers |
| Birth Date: | 4 November 1873 |
| Birth Place: | Stormont County, Ontario |
| Death Place: | Lancaster, Ontario |
| Occupation: | Farmer |
| Spouse: | Laura Clifford McGregor |
Duncan Alexander Ross (November 4, 1873 - 1954) was an Ontario farmer and political figure. He represented Glengarry in the Legislative Assembly of Ontario from 1919 to 1923 as a United Farmers member.
He was born in Charlottenburg Township, Ontario, the son of Donald Ross, and was educated at the Ontario Agricultural College in Guelph. Ross married first Jemima Dingwall and second Laura Clifford McGregor. He was a director for the Glengarry Mutual Fire Insurance Company. He served as a member of the Canadian Farm Loan Board (later Farm Credit Canada) from 1943 to 1948. He died in 1954 and was buried at North Branch Cemetery in Martintown, Ontario.