Alfred Joseph (Alf) Blackwell (9 April 1876 – 16 October 1955) was an Australian politician who represented the South Australian House of Assembly multi-member seat of West Torrens from 1918 to 1938 for the Australian Labor Party, excluding the 1931-34 Labor split, when he sat with the splinter Parliamentary Labor Party. He was elected to the House of Assembly at the 1918 election. He was a member of the Parliamentary Standing Committee on Railways from 1926 to 1927, and of the Parliamentary Standing Committee on Public Works from 1927 to 1938.