| O. D. Guilfoil | |
| State Senate: | Washington |
| District: | 19th |
| Term Start1: | November 6, 1889 |
| Term End1: | January 7, 1891 |
| Predecessor1: | Constituency established |
| Successor1: | L. F. Thompson |
| Birth Name: | Oscar Daniel Guilfoil |
| Birth Date: | 8 July 1863 |
| Birth Place: | Rhinebeck, New York, U.S. |
| Death Place: | Ogdensburg, New York, U.S. |
| Party: | Republican |
Oscar Daniel Guilfoil, Sr. (July 8, 1863 – December 23, 1955) was an American politician in the state of Washington. He served in the Washington State Senate from 1889 to 1891.[1] [2] He died at a hospital in Ogdensburg, New York in 1955, where he had lived the last 10 years of his life. His obituary in The Post-Standard erroneously stated his age at death as 100, as his family stated that his birth date was unknown. He was buried in Rhinebeck.[3]