Sidney Wainman "Sid" O'Flaherty (2 July 1886 – 18 November 1967) was an Australian politician. Born in Silverton, South Australia, he was educated at the Adelaide School of Mines before becoming an architect and accountant, and later a secretary with the Miscellaneous Workers' Union. In 1918, he was elected to the South Australian House of Assembly as the Labor member for Murray, serving until 1921. In 1943 he became President of the South Australian Labor Party, but later that year he was elected to the Australian Senate as a Labor Senator for South Australia. He held the seat until his retirement in 1961. O'Flaherty died in 1967.