Jack Barnett may refer to:
Jack Barnett (baseball) (1879–1923), American baseball player Jack Barnett (footballer) (1899–1979), Australian rules footballer Jack Barnett (politician) (1869–1945), full name John "Jack" Septimus Barnett, deputy mayor of Christchurch from 1938 to 1941 John Barnett (rugby) (1881–1918), known as Jack, Australian rugby union and rugby league player Jack Barnett, member of the English band These New Puritans