John Gannon may refer to: John Gannon (Australian politician) (1830–1887), member of the New South Wales Legislative Assembly John Gannon (footballer) (born 1966), English footballer John D. Gannon (1948–1999), American computer scientist John A. Gannon (1923–1997), American labor union leader Sam Gannon (born 1947), real name John Gannon, Australian cricketer John Mark Gannon (1877–1968), American clergyman of the Roman Catholic Church John Gannon (Idaho politician), Idaho state representative John Gannon (Vermont politician), Vermont state Representative