William Nelson may refer to:
William Nelson (athlete) (born 1984), American steeplechaser
William Nelson (governor) (1711–1772), American Colonial governor of Virginia
William Nelson, great-grandfather of Horatio Nelson
William Nelson (MP), Member of Parliament (MP) for City of York
William Nelson (New York congressman) (1784–1869), U.S. Congressman for New York
William Nelson (Wisconsin) (1839–?), member of the Wisconsin State Senate
William Nelson (wrestler), American wrestler
William Nelson, 1st Earl Nelson (1757–1835), elder brother of Horatio Nelson, 1st Viscount Nelson
William "Bull" Nelson (1824–1862), Union army general in the American Civil War
William E. Nelson (born 1941), Canadian environmentalist
William E. Nelson (died 1991), private pilot murdered, dismembered, and cannibalized by his wife Omaima Nelson
William G. Nelson, professor at Johns Hopkins University
William H. Nelson (born 1944), American businessman
Harold Nelson (athlete) (William Harold Nelson, 1923–2011), New Zealand runner
William L. Nelson (1875–1946), U.S. Congressman for Missouri
William L. Nelson (Medal of Honor) (1918–1943), World War II Medal of Honor recipient
William T. Nelson (1908–1994), U.S. Navy rear admiral
William Layton Nelson (born 1945), American singer and musician
William Rockhill Nelson (1841–1915), American journalist and publisher
William Nelson (industrialist) (1843–1932), New Zealand farmer and industrialist
Willie Nelson (born 1933), U.S. guitarist, songwriter and country singer
Billy Nelson (actor) (1903–1973), American actor
Billy Bass Nelson (born 1951), American musician, member of the P-funk All Stars
Edward William Nelson (1855–1934), American naturalist