Sir Leslie Cannon CBE (21 February 1920 – 9 December 1970) was a prominent British trade union official and served as General President of the Electrical Trades Union from 1963 to 1970. He was born in Wigan, the son of a coal miner, and became a Communist activist, and trade union leader; member of Electrical Trades Union Executive Council, North Lancashire and Merseyside, 1948–1954. He left the Communist Party of Great Britain in 1956. In 1961 he uncovered an ETU ballot rigging scandal, and successfully sued the union. Cannon became president of the ETU in September 1963, a post left vacant by disgraced former president Frank Foulkes.
In his time as leader of the ETU, he took part in a merger with the plumbers' union to create the EETPU.
Cannon died from cancer, aged 50.