William, Will, Willie, Bill or Billy Brown may refer to:
Academics
William Brown (physician) (1748–1792), American physician
William Brown (veterinarian) (1861–1931), English veterinarian and activist
William Brown (plant pathologist) (1888–1975), British mycologist and plant pathologist
William Brown (psychologist) (1881–1952), British psychologist
William Fuller Brown Jr. (1904–1983), American physicist
W. G. Brown, Canadian mathematician
William Harvey Brown (1862–1913), American naturalist
William Jethro Brown (1868–1930), Australian jurist and professor of law
William L. Brown (geneticist) (1913–1991), American geneticist
W. Norman Brown (1892–1975), American Indologist and Sanskritist
William Brown (industrial relations expert) (1945–2019), British academic, Master of Darwin College, Cambridge
William Yancey Brown (born 1948), American zoologist and attorney
William Brown (author) (born 1977), British film academic and author
Arts and Entertainment
William Brown (composer) (1790–1884), American composer and flutist
William Alexander Brown (1790–1884), African-American playwright and theatrical producer
William Mason Brown (1828–1898), American artist
William Kellock Brown (1856–1934), Scottish sculptor
William J. Brown (architect) (died 1970), American architect
Willie Brown (musician) (1900–1952), American delta blues guitarist and singer
William Theophilus Brown (1919–2012), American artist
William Brown (tenor) (1938–2004), American opera singer
Billy Brown (Irish musician) (1943–1999), Irish musician and artist, and member of The Freshmen
Billy Brown (singer) (born 1944), member of American rhythm and blues band Ray, Goodman & Brown
W. Earl Brown (born 1963), American character actor
Guillermo E. Brown (born 1976), American drummer and multi-disciplinary performer
William Brown, better known as Compa, British electronic musician
Bill Brown (filmmaker) (active since 1994), American filmmaker and author
William H. Brown Jr. (1917–1982), American television director and producer, radio dramatist, and composer
Bille Brown (William Gerald Brown, 1952–2013), Australian actor, director and playwright
Sportspeople
American football
Bill Brown (American football quarterback) (1917–2011), professional player for the Brooklyn Dodgers (NFL)
Bill Brown (linebacker) (1936–1989), American football player in 1960 Boston Patriots season
Bill Brown (American football) (1938–2018), American football running back
Willie Brown (American football) (1940–2019), American football Hall-of-Fame cornerback
Willie Brown (American football, born 1942) (1942–2018), Tampa Bay Buccaneers coach
Billy Brown (American football) (born 1993), American football tight end
Association football
William Brown (goalkeeper) (fl. 1889–1895), English footballer
William Brown (footballer, born 1865), English footballer
William Brown (footballer, born 1874) (1874–1940), English footballer and cricketer
William Brown (footballer, born 1876), Scottish footballer
William Brown (footballer, born 1885), Scottish footballer
William Brown (footballer, born July 1885) (1885–1915), Scottish footballer
William Brown (footballer, born 1889), Scottish footballer
William Brown (footballer, born 1897), Scottish footballer
Willie Brown (footballer, born 1900) (1900–1977), Scottish footballer (Rochdale AFC, Torquay United)
Billy Brown (footballer, born 1900) (1900–1985), English professional footballer
Bill Brown (footballer, born 1902) (1902–1985), Scottish footballer
William Brown (footballer, born 1907) (1907–1976), English footballer and sprinter
Buster Brown (footballer) (William Ian Brown, 1910–1993), footballer who played in the Football League
William Brown (footballer, born 1912) (1912–2008), Scottish footballer
Willie Brown (footballer, born 1922) (1922–1978), Scottish football player (Preston North End, Grimsby Town) and manager (Barrow AFC)
Willie Brown (footballer, born 1928) (1928–2017), Scottish footballer (Forfar Athletic, Accrington Stanley)
Bill Brown (footballer, born 1928) (1928–2010), English footballer
Bill Brown (footballer, born 1931) (1931–2004), Scottish international football (soccer) goalkeeper (Dundee, Tottenham Hotspur)
Willie Brown (footballer, born 1938), Scottish footballer (Accrington Stanley, Chester City, Greenock Morton)