Robert, Rob or Bob Williams may refer to:
Arts
Film and television
- Rob Williams (filmmaker), American film director
- Robert Williams (actor) (1894–1931), American stage and film actor
- Robert B. Williams (actor) (1904–1978), American film actor
- Robert Williams, fictional character in Another Earth
Literature
- Robert Williams (Robert ap Gwilym Ddu) (1767–1850), Welsh language poet
- Robert Williams (Trebor Mai) (1830–1877), Welsh language poet
- Rob Williams (comics), British comic writer
- Rob Williams (entrepreneur) (1979–2009), partner of business Dolphin Music
- Robert Moore Williams (1907–1977), American writer
Musicians
- Robbie Williams (born 1974), British pop singer
- Chocolate Williams (né Robert Williams, Jr.; 1916–1984), jazz bassist and blues vocalist from Harlem
- Robert S. Williams (born 1949), bassoon player of the Detroit Symphony Orchestra
- Robert Williams (drummer) (born 1955), Captain Beefhearts Magic Band, Hugh Cornwell, and as a solo artist
- Robert Pete Williams (1914–1980), American blues musician
- Meek Mill (Robert Rihmeek Williams, born 1987), American hip hop artist
Various
- Robert Williams (artist) (born 1943), underground cartoonist and painter
- Rob Williams (radio personality), The Rob, Arnie, and Dawn Show
Politicians
- Sir Robert Williams, 2nd Baronet (c. 1627–1678), Member of Parliament for Carnarvonshire, 1656–1658, and for Carnarvon Boroughs, 1659
- Robert Williams (died 1763) (c. 1695–1763), Member of Parliament for Montgomeryshire, 1740–1741 and 1742–1747
- Sir Robert Williams, 9th Baronet of Penryn (1764–1830), Member of Parliament for Carnarvonshire, 1790–1826, and for Beaumaris, 1826–1831
- Robert Williams (1735–1814), Member of Parliament for Dorchester 1807–1812
- Robert Williams (1767–1847), Member of Parliament for Wootton Basset, 1802–1807, Grampound, 1808, Kilkenny, 1809–1812, and Dorchester, 1812–1835
- Robert Williams (1811–1890), Member of Parliament for Dorchester, 1835–1841
- Sir Robert Williams, 1st Baronet, of Bridehead (1848–1943), Conservative Member of Parliament for West Dorset, 1895–1922
- Robert L. Williams (1868–1948), American politician, governor of Oklahoma
- Robert Williams (Victorian politician) (1870–1938), Australian politician
- Bo Williams (Robert Warren Williams, born 1938), mayor of Shreveport, Louisiana
- Robert Williams (Mississippi politician) (1773–1836), Governor of the Mississippi Territory
- Robert Williams (North Carolina politician) (1773–1821), U.S. Representative from North Carolina
- Robert P. Williams (1841–1910), State Treasurer of Missouri, 1901–1905
- Robert R. Williams (politician), 1930s mayor of Miami, Florida
- Robert Q. Williams (born 1964), member of the South Carolina House of Representatives
- Robert Arthur Williams (born 1933), consultant and political figure in British Columbia
- Bob Williams (politician) (born 1951), American politician and state senator in West Virginia
- Robert Wynn Williams (1864–1929), solicitor and member of the Queensland Legislative Assembly
Sportsmen
- Robert Williams (English cricketer) (born 1970), former English cricketer
- Rob Williams (rower) (born 1985), British rower
- Bobby Williams (footballer, born 1932), English footballer for Chester City
- Bobby Williams (footballer, born 1940), English footballer
- Bobby Williams (Scottish footballer) (died 1916), Scottish footballer
- Bobbie Williams (rugby player) (1865–1967), Welsh international rugby union player
- Robert Williams (cornerback) (born 1962), former American football cornerback
- Robert Williams (archer) (1841–1914), American archer
- Robert Williams (baseball) (1917–2000), American baseball pitcher and infielder in the Negro Leagues
- Bobby L. Williams (1895–1978), American baseball shortstop and manager in the Negro Leagues
- Robert Williams (quarterback), football player for Notre Dame, 1956–1958
- Bob Williams (badminton), badminton player in the 1952 Thomas Cup
- Bob Williams (baseball) (1884–1962), baseball player for the New York Highlanders/Yankees
- Bob Williams (basketball, born 1931), former NBA player for the Minneapolis Lakers
- Bob Williams (basketball, born 1953), men's basketball head coach at UC Santa Barbara
- Bob Williams (quarterback) (1930–2016), football player for Notre Dame
- Bob Williams (coach) (1877–1957), college American football coach
- Bob Williams (racing driver), former NASCAR Cup Series driver
- Bob Williams (American football coach), at Livingston State Teachers College, now University of West Alabama, 1952
- Bobby Williams (born 1958), tight end, coach
- Bobbie Williams (born 1976), American football guard
- Rob Williams (basketball) (1961–2014), American basketball player
- Bob Williams (rugby) (1886–1969), Australian rugby league footballer
- Bob Williams (Australian rules footballer) (1913–2004), Australian rules footballer with Hawthorn
- Robert Williams (South African cricketer) (1912–1984), South African cricketer
- Robert Williams (basketball), basketball player
Criminals
- Robert E. Williams (criminal) (died 1997), murderer in Nebraska; see Capital punishment in Nebraska
- Robert W. Williams (1951–1983), American murderer
Military
- Robert B. Williams (1901–1977), World War II general in the United States Army Air Forces
- Robert Williams (general) (1829–1901), Adjutant General of the U.S. Army from 1892 to 1893
Others
- Sir Robert Williams, 1st Baronet, of Park (1860–1938), Scottish mining engineer, explorer of Africa, and railway developer in Angola
- Robert Williams (Archdeacon of Carmarthen) (1863–1938), professor of history and archdeacon
- Robert Williams (trade union leader) (1881–1936), British trade union organiser
- Robert Williams (physician) (1916–2003), Welsh pathologist
- Robert Williams (chemist) (1926–2015), Professor of Oxford University
- Robert A. Williams, Jr., Native author and legal scholar
- Robert F. Williams (1925–1996), American civil rights activist
- Robert R. Williams (1886–1965), American chemist who first synthesized vitamin B1
- Robert Williams (geometer) (born 1942), American designer, mathematician, and architect
- Robert Williams (gay priest) (1955–1992), first openly gay male priest in the Episcopal Church
- Robert Williams (robot fatality), died 1979, the first person to be killed by a robot
- Robert Williams (psychologist) (born 1930), second President of the Association of Black Psychologists
- Robert Dewi Williams (1870–1955), Welsh schoolteacher, Presbyterian minister and author
- Robert H. Williams, environmental scientist at the Princeton Environmental Institute
- Robert Williams (Archdeacon of Gower) (born 1951)
- Robert Williams (astronomer) (born 1940), director of STScI 1993–98; president of IAU, 2009–2012
- Robin M. Williams (1919–2013), New Zealand scientist, academic and civil servant