Jack Mortimer (30 October 1912 – 8 February 1973) was an Australian politician. He received a primary education before becoming a farmer in South Australia. He served in the military from 1942 to 1946 and returned as a waterside worker in Port Lincoln where he was a branch secretary of the Waterside Workers' Federation. In 1963, he was elected to the Australian House of Representatives as the Labor member for Grey. He held the seat until his defeat in 1966, after which he became a businessman in Port Lincoln. Mortimer died by drowning at Port Hedland in 1973.