William Smith is the name of:

• William Smith (1697–1769), father of John Smith, Doctor Thomas Smith, Joshua Hett Smith, and Chief Justice William Smith
• William Smith (abolitionist) (1756–1835), dissenter and British M.P. whose constituencies included Camelford, Sudbury, and Norwich
• William Smith (actor) (born 1934)
• William Smith (boxer)
• William Smith (chief justice) (1728–1793), historian, Chief Justice of the Province of New York, and Chief Justice of the Supreme Court of Canada
• William Smith (geologist) (1769–1839)
• William Smith (lexicographer) (1813–1893)
• William Smith (mariner) (born c. 1775, fl. 1819–1820), British mariner and discoverer of the South Shetland Islands
• William Smith (Maryland) (1728–1814), United States representative from Maryland from 1789 to 1791
• William Smith (Mormonism), also known as William B. Smith, younger brother of the founder of Mormonism, Joseph Smith, Jr., and a leader in the Latter Day Saint movement
• William Smith (scholar) (1711–1787), classical scholar and Dean of Chester
• William Smith (South Carolina representative) (1751–1837), United States representative from South Carolina from 1797 to 1798
• William Smith (South Carolina senator) (1762–1840), United States senator from South Carolina from 1815 to 1830
• William Smith (swimmer)
• William Smith (Virginia), United States representative from Virginia from 1821 to 1827
• William Alden Smith (1859–1932), United States representative from Michigan from 1895 to 1906 and United States senator from Michigan from 1905 to 1918
• William Alexander Smith (1828–1888), United States representative from North Carolina from 1873 to 1874
• Sir William Alexander Smith (Boys Brigade) (1854–1914), founder of the Boys' Brigade
• William Charles Smith (1877–1946), a.k.a. Razor Smith, cricket player from Surrey
• William E. Smith, Governor of Wisconsin from 1878 to 1882
• William "Extra Billy" Smith (1797–1887), Governor of Virginia (1846–1849, 1864–1865) and Confederate general
• William Ephraim Smith (1829–1890), United States representative for Georgia from 1875 to 1880
• William Farrar Smith, Union Army general
• William Smith (Medal of Honor) (1838-?), American Civil War sailor and Medal of Honor recipient
• William Smith (Medal of Honor, 1869), American Indian Wars soldier and Medal of Honor recipient
• William French Smith, United States Attorney General from 1981 to 1985
• William H. Smith, Governor of Alabama from 1868 to 1870
• William H. Smith (Medal of Honor), American Indian Wars soldier and Medal of Honor recipient
• William Harrison Smith, Medal of Honor winner in World War II
• William Jay Smith (1823–1913), United States representative from Tennessee from 1869 to 1870
• William John Smith (born 1942), a.k.a. Billy Smith (rugby league footballer), champion Australian rugby league halfback of 1960s and 1970s
• William Kennedy Smith (born 1960), Kennedy family scion, physician, acquitted of rape in 1991
• William Laird Smith, Australian representative for Denison from 1910 to 1922
• William Loughton Smith (1758–1812), United States representative from South Carolina from 1789 to 1798
• William Nathan Harrell Smith (1812–1889), United States representative from North Carolina from 1859 to 1860
• William Orlando Smith (1859–1932), United States representative from Pennsylvania from 1903 to 1906
• William Robert Smith (1863–1924), United States representative from Texas from 1903 to 1916
• William Robertson Smith (1846–1894), philologist, physicist, archaeologist, and Biblical critic
• William Russel Smith (1815–1896), United States representative from Alabama from 1851 to 1856
• William Stephens Smith (1755–1816), United States representative from New York from 1813 to 1816

William Smith may also be the name of:

• Amor De Cosmos (1825–1897), born William Alexander Smith, Premier of British Columbia
• William Smith (c. 1872–1941), Master of the SS Sauternes, English merchant seaman killed in World War II