William J. Grattan (May 20, 1876 – December 6, 1938) was an American lawyer and politician from New York.
He was born in West Troy, Albany County, New York.
He graduated in 1898, was admitted to the bar the same year, and practiced law in Albany.
Grattan was a member of the New York State Assembly (Albany Co., 4th D.) in 1903, 1904, 1905 and 1906.
This article about a member of the New York State Senate is a stub.