William McGregor may refer to:

• William McGregor (football) (1846–1911), founder of the Football League
• William McGregor (judoka) (born 1949), Canadian Olympic judoka
• William McGregor (politician) (1836–1903), Canadian businessman and political figure
• William McGregor (director) (born 1987), British screenwriter and director
• William B. McGregor (born 1952), Australian linguist and professor
• William Roy McGregor (1894–1977), New Zealand zoologist and early conservationist
• Will McGregor (Wild Roses), a character on Wild Roses
• Billy McGregor (1876–1919), Australian rules footballer
• Bill McGregor, football player in the 1973 CFL Draft
• Willie McGregor, Mansfield Town F.C. player
• Billy McGregor (ice hockey), ice hockey player in the 1938 Memorial Cup

• William MacGregor (disambiguation)
• William Gregor (1761–1817), British clergyman and mineralogist