William Millar
William Millar may refer to:
- William Millar (transportation executive), former President of the American Public Transportation Association
- William Millar (British Army officer), British Royal Artillery officer
- William Millar (politician), Irish-born Wisconsin politician
- Billy Millar (rugby union), South African rugby union player
- Willie Millar, Scottish footballer
- Billy Millar (footballer, born 1906), Irish international footballer
- Billy Millar (footballer, born 1924), Scottish footballer
- William Millar, Irish-born American actor, known as Stephen Boyd
- Will Millar, Irish-Canadian singer