Jack Barnett

• Jack Barnett (baseball), American baseball player
• Jack Barnett (footballer), Australian rules footballer
• Jack Barnett (politician), full name John "Jack" Septimus Barnett, deputy mayor of Christchurch from 1938 to 1941
• John Barnett (rugby), known as Jack, Australian rugby union and rugby league player
• Jack Barnett, member of the English band These New Puritans