William Ambrose Prendergast (May 25, 1867 – June 20, 1954) was an American businessman and politician from New York.

[2] Their children were Eleanor, William A. Jr., and Thomas H.[3] Prendergast worked as a secretary for the National Association of Credit Men from 1899 to 1904.

In 1910, he became secretary and general manager of the Lands Co. of Depew and president of the Island Cities Real Estate Co.[4] In 1918, he became chairman of the New York and Honduras Rosario Mining Company.

[2] In the 1897 United States House of Representatives special election, Prendergast was the Republican candidate for New York's 3rd congressional district.

He supported Theodore Roosevelt's 1912 presidential campaign, presenting his name for nomination at the 1912 Progressive National Convention.