John Callaghan
John Callaghan may refer to:
- John Callaghan (physician) (1923–2004), Canadian cardiac surgeon
 - John Callaghan (Galway), Irish murder victim
 - John Callaghan (musician) (born 1969), British musician
 - John Callaghan (screenwriter), see List of Republic of Doyle episodes
 - John Callaghan (footballer), see List of Sheffield Wednesday F.C. players