William Nicholson may refer to:
- William Nicholson (bishop) (1591–1672), Bishop of Gloucester
- William Nicholson (chemist) (1753–1815), English chemist and writer
- William Nicholson (naval officer) (c. 1790–1872), U.S. naval officer
- William Nicholson (Australian politician) (1816–1865), Mayor of Melbourne and Premier of Victoria
- William Nicholson, 1st Baron Nicholson (1845–1918), British Field Marshal and Chief of the Imperial General Staff
- William Nicholson (artist) (1872–1949), English painter
- William Nicholson (writer) (born 1949), British screenwriter, playwright, and novelist
- William Nicholson (scientist), developed a "rotating doubler" influence machine, see Cox's timepiece
- William Newzam Nicholson (1816–1899), British Member of Parliament for Newark, 1880–1885
- William Nicholson (distiller) (1825–1909), British Member of Parliament for Petersfield, 1866–1874 and 1880–1885, cricketer and cricket benefactor
- William Nicholson (Royal Navy officer) (1863–1932), British admiral
- William Brinsley Nicholson (1877–1957), New Zealand clerk, local politician, builder, journalist and editor
- William Graham Nicholson (1862–1942), British Liberal Unionist and later Conservative Party politician
- William Rufus Nicholson (1822–1901), bishop of the Reformed Episcopal Church