Duncan T. O'Brien (March 28, 1895 – September 14, 1938) was an American politician from New York.
He was a member of the New York State Senate (19th D.) from 1923 until his death in 1938, sitting in the 146th, 147th, 148th, 149th, 150th, 151st, 152nd, 153rd, 154th, 155th, 156th, 157th, 158th, 159th, 160th and 161st New York State Legislatures; and was Chairman of the Committee on Military Affairs from 1923 to 1924.
|New York State Senate|
| New York State Senate
Charles D. Perry