John Gerald "Jack" Breheny (17 May 1910 – 11 February 2009) was an Australian politician.
He was born in Toowoomba in Queensland.
In 1951 he was elected to the Tasmanian House of Assembly as a Liberal member for Darwin (later Braddon) in a recount following Jack Chamberlain's resignation.
He served until his defeat in 1972, and was then an Ulverstone councillor from 1976 to 1991.