McWilliam is a surname. Notable people with the surname include:
Candia McWilliam (born 1955), Scottish writer
Colin McWilliam (1928–1989), Scottish academic and writer
F. E. McWilliam (1909–1992), British sculptor
George Roy McWilliam (1905–1977), Canadian politician
John McWilliam (1941–2009), Scottish politician
Peter McWilliam (1879–1951), Scottish footballer
Richard McWilliam (1953–2013), American businessman