William Belknap may refer to:
William W. Belknap (1829–1890), lawyer, soldier, government administrator and the United States Secretary of War William G. Belknap (1794–1851), United States Army general, father of William W. Belknap William Richardson Belknap (1849–1914), president of the Belknap Hardware and Manufacturing Company William Burke Belknap (1885–1965), American entrepreneur, son of William W. Belknap