John Duffy
John Duffy may refer to:
Sportspeople
- John Duffy , English football centre half for Bradford City
- John Duffy , Scottish football right back for Clyde and Norwich
- John Duffy , Scottish football wing half for Celtic, Arbroath and Southend
- John Duffy, Scottish football wing half for Raith, Dunfermline, Darlington and Australian clubs
- John Duffy, Gaelic football player
- John Duffy , rugby league player
- John Duffy , American soccer player
Others
- John Duffy , American composer
- John Duffy , American economist
- John Duffy , American gang member, member of the North Side Gang
- John Duffy, Canadian writer and political strategist
- John Duffy and David Mulcahy, the Railway Rapists, British rapists and murderers
- John A. Duffy, American bishop
- John F. Duffy, legal academic
- John Gavan Duffy, Australian politician
- John J. Duffy, American Medal of Honor recipient
- John J. Duffy Jr., American criminal defense attorney
- John Duffy , University professor & author of several books on U.S. medical history