McWilliams is a surname. Notable people with the surname include:
Alfred McWilliams (b. 1844, d. unknown), Canadian politician from Prince Edward Island
Bill McWilliams (1910–1997), American professional baseball player
Brendan McWilliams (1944–2007), Irish meteorologist and science writer
Carey McWilliams (1905–1980), American author, editor, and lawyer
Carey McWilliams (b. 1973), American author, marksman, and skydiver
Caroline McWilliams (b. 1945), American television actress; former wife of Michael Keaton
Christopher 'Crip' McWilliams (1963–2008), Irish nationalist; convicted of the murder of the LVF leader Billy Wright
Cynthia Kaye McWilliams (contemporary), American actress
David McWilliams (contemporary), American college football coach
David McWilliams (1945–2002), Northern Irish singer, songwriter, and guitarist
David McWilliams (b. 1966), Irish economist, commentator, and author
Derek McWilliams (b. 1966), Scottish professional football player
Edmund McWilliams (contemporary), American diplomat and ambassador
Elsie McWilliams (1896-1985), American songwriter
Eric McWilliams (b. 1950), American professional basketball player
Fleming McWilliams (contemporary), American singer and songwriter
George McWilliams (1865–1907), Australian doctor and MP
Jackie McWilliams (b. 1964), Irish Olympic field hockey player
Jeremy McWilliams (b. 1964), Irish motorcycle road racer
Joe McWilliams (1904–1996), American inventor, industrial engineer, and nationalist
John D. McWilliams (1891–1975), American politician from Connecticut; U.S. Representative 1943–45
Johnny McWilliams (b. 1972), American professional football player
Larry McWilliams (b. 1954), American professional baseball player
Monica McWilliams (b. 1954), Northern Ireland academic and politician
Peter McWilliams (1949–2000), American marijuana activist and writer
Rhys McWilliams (b. 1985), English professional ice hockey player
Roland Fairbairn McWilliams (1874–1957), Canadian politician from Manitoba
Ruben McWilliams (1901–1984), New Zealand All Blacks rugby player
Shorty McWilliams (1926–1997), American football player
Taj McWilliams-Franklin (b. 1970), American professional women’s basketball player
William McWilliams (1856–1929), Australian politician from Tasmania
Wilson Carey McWilliams (1933–2005), American political scientist and writer