Joel Barnett, Baron Barnett, PC (born 14 October 1923), is a Labour member of the House of Lords. He was made a Life Peer in 1983.

He was formerly a Member of Parliament for Heywood and Royton, and served as Chief Secretary to the Treasury from 1974 to 1979 gaining a seat in the cabinet from 1977 onwards. During this time he oversaw the devising of what is known as the Barnett Formula by which Scotland and Wales receieve a higher proportion of government spending per head than England, due to the geographic problems of service provision. He has since joked about the strange and unexpected form of immortality that has been accorded to him by 'having his own Formula'.