William Duffy, Bill Duffy or Billy Duffy may refer to: Bill Duffy (basketball), American basketball player and player agent Bill Duffy (sportsman) (1866–1959), Australian sportsman Billy Duffy (born 1961), English musician Billy Duffy (hurler) (1931–2005), Irish hurler William Duffy, a pseudonym of William Dufris (1958–2020), an American voice actor William Duffy (bishop), English Roman Catholic bishop William Duffy (politician) (1865–1945), Irish nationalist politician William James Duffy (1888–1946), Canadian politician William J. Duffy (1916–2013), American jurist and legislator