William Duffy

• Bill Duffy, American basketball player and player agent
• Bill Duffy , Australian sportsman
• Billy Duffy, English musician
• Billy Duffy , Irish hurler
• William Duffy, a pseudonym of William Dufris, an American voice actor
• William Duffy, English Roman Catholic bishop
• William Duffy , Irish nationalist politician
• William James Duffy, Canadian politician
• William J. Duffy, American jurist and legislator