Lindsay Gordon Riches, CMG (18 February 1904 – 7 June 1972) was a South Australian politician. He was a Labor Party member of the South Australian House of Assembly from 1933 to 1970, representing the electorates of Newcastle (1933-1938) and Stuart (1938-1970). He was Speaker of the South Australian House of Assembly from 1965 to 1968 under Frank Walsh and Don Dunstan. He was also a long-time mayor of the City of Port Augusta from 1936 to 1970, with Port Augusta gaining city status during his tenure.