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^[1] and returned as a waterside worker in Port Lincoln where he was a branch secretary of the Waterside Workers' Federation.^[2] 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.^[3][4]

Mortimer married Melva Bähr, of Ceduna, in 1939. They had a daughter and a son, and farmed at Karkoo.