William Mullins may refer to:
- William Mullins (Mayflower passenger)
- William Mullins, 2nd Baron Ventry, Anglo-Irish politician and peer
- William D. Mullins, American politician and baseball player
- William W. Mullins, American physicist and materials scientist
- Willie Mullins, Irish racehorse trainer and jockey
- Bill Mullins, Australian rugby league player
- Bill Mullins (equestrian), Irish equestrian