John O'Hara (1905–1970) was an American writer of Appointment in Samarra, Butterfield 8, and many short stories.
John O'Hara may also refer to:
- John O'Hara (Brooklyn politician), American lawyer
- John O'Hara (musician), English keyboardist and conductor, currently member of Jethro Tull
- John O'Hara (singer), leader of O'Hara's Playboys (a Glasgow band in the 1960s-1970s)
- John O'Hara (soccer, born 1959), American soccer defender
- John O'Hara (footballer, born 1981), Irish professional soccer goalkeeper
- John O'Hara (American football) (1944–1992), American college football coach
- John O'Hara (wrestler) (1913–1983), Australian Olympic wrestler
- Sir John Ailbe O'Hara, Northern Ireland High Court judge
- John Bernard O'Hara (1862–1927), Australian poet and schoolmaster
- John Francis O'Hara (1888–1960), American archbishop and cardinal
- John Joseph O'Hara (born 1946), American prelate of the Roman Catholic Church
- John Myers O'Hara (1870–1944), American poet
- Jack O'Hara (John James O'Hara, 1866–1931), Australian rules footballer who