| William T. O'Neil | |
| Birth Date: | 7 February 1850 |
| Birth Place: | Brighton, New York |
| Death Place: | St. Regis Falls, New York |
| Signature: | Signature of William Thomas O'Neil (1850–1909).png |
| Office1: | Member of the New York State Senate |
| Constituency1: | 34th District |
| Term Start1: | 1907 |
| Term End1: | 1909 |
| Office2: | Member of the New York State Assembly |
| Constituency2: | Franklin County |
| Term Start2: | 1882 |
| Term End2: | 1885 |
William Thomas O'Neil (February 7, 1850 – May 5, 1909) was an American politician from New York.
William T. O'Neil was born in Brighton, Franklin County, New York on February 7, 1850. He attended the common schools and Fort Edward Collegiate Institute. Then he engaged in the lumber business and farming. He lived in St. Regis Falls, a hamlet in the town of Waverly.[1]
O'Neil was Supervisor of Waverly in 1881; and a member of the New York State Assembly (Franklin Co.) in 1882, 1883, 1884 and 1885.[1]
He was a presidential elector in 1900.[2]
He was a member of the New York State Senate (34th D.) from 1907 until his death in 1909, sitting in the 130th, 131st and 132nd New York State Legislatures. He suffered a stroke, and had to be rolled into the Senate chamber in a wheel-chair in January and February 1909. In March, he became too ill to attend the legislative session, and died on May 5, 1909, at his home in St. Regis Falls.[3]