William Nicholson may refer to:
- William Nicholson (English bishop) (1591–1672), Bishop of Gloucester
- William Nicholson (chemist) (1753–1815), English chemist, publisher, and inventor
- William Nicholson (artist, born 1781) (1781–1844), English portrait-painter and etcher
- William Nicholson (poet) (1782–1849), Scottish poet, known as the Bard of Galloway
- William Nicholson (U.S. Navy officer) (c. 1790–1872), U.S. Navy officer
- William Adams Nicholson (1803–1853), English architect
- William Newzam Nicholson (1816–1899), British Member of Parliament for Newark, 1880–1885
- William Nicholson (Australian politician) (1816–1865), Mayor of Melbourne and Premier of Victoria
- William Nicholson (American bishop) (1822–1901), American bishop of the Reformed Episcopal Church
- William Nicholson (distiller) (1824–1909), British distiller, politician, cricketer and cricket benefactor
- William Nicholson, 1st Baron Nicholson (1845–1918), British field marshal and Chief of the Imperial General Staff
- William Jones Nicholson (1856–1931), U.S. Army general
- William Graham Nicholson (1862–1942), British Liberal Unionist and later Conservative Party politician
- Sir William Nicholson (Royal Navy officer) (1863–1932), British admiral
- William H. Nicholson (1869–1911), first African American fireman in the New York City Fire Department
- Sir William Nicholson (artist) (1872–1949), English painter and engraver
- William Nicholson (journalist) (1877–1957), New Zealand clerk, local politician, builder, journalist and editor
- Willie Nicholson (fl. 1924–1936), Scottish footballer
- William L. Nicholson (1926–2020), U.S. Air Force general
- William Nicholson (sound engineer) (born 1937), American film sound engineer
- William Nicholson (writer) (born 1948), British screenwriter, playwright and novelist