John Duffy

John Duffy may refer to:

Sportspeople

 * John Duffy (footballer, born 1886) (1886–?), English football centre half for Bradford City
 * John Duffy (footballer, born 1922) (1922–1996), Scottish football right back for Clyde and Norwich
 * John Duffy (footballer, born 1929) (1929–2004), Scottish football wing half for Celtic, Arbroath and Southend
 * John Duffy (footballer, born 1943), Scottish football wing half for Raith, Dunfermline, Darlington and Australian clubs
 * John Duffy (Gaelic footballer), Gaelic football player
 * John Duffy (rugby league) (born 1980), rugby league player
 * John Duffy (soccer) (1905–1984), American soccer player

Others

 * John Duffy (composer) (1926–2015), American composer
 * John Duffy (economist) (born 1964), American economist
 * John Duffy (mobster) (died 1924), American gang member, member of the North Side Gang
 * John Duffy (writer), Canadian writer and political strategist
 * John Duffy and David Mulcahy (both born 1959), the Railway Rapists, British rapists and murderers
 * John A. Duffy (1884–1944), American bishop
 * John F. Duffy (born 1963), legal academic
 * John Gavan Duffy (1844–1917), Australian politician
 * John J. Duffy, American Medal of Honor recipient
 * John J. Duffy Jr. (1933–2019), American criminal defense attorney
 * John Duffy (medical historian) (1915–1996), author of several medical history books