William Cain
William Cain may refer to:
- William Cain (American politician), lieutenant governor of South Carolina
- William Cain (Australian politician), mayor of Melbourne and Victorian parliamentarian
- William Cain (sea captain), Manx master mariner
- Sir William Cain, 1st Baronet, English brewer and philanthropist
- William Cain (cricketer), Australian cricketer
- William Cain (deemster), Manx judge
- Bill Cain (athletic director), American athletic director
- Bill Cain (basketball), player in Iowa State Cyclones men's basketball
- Bill Cain, American playwright