William Nelson (June 29, 1784 – October 3, 1869) was an American lawyer and judge from Westchester County, New York.
Born in Hyde Park, Dutchess County, New York, on June 29, 1784, Nelson attended the common schools and was graduated from Poughkeepsie Academy.
He studied law and was admitted to the bar in 1807, and commenced practice in Peekskill, Westchester County, New York.
For thirty years he served as district attorney for Putnam, Rockland, and Westchester Counties.
He is interred at Hillside Cemetery, Cortlandt town, Westchester County, New York.