Robert Ivan Lucas is an Australian former politician and a former member of the South Australian Legislative Council between the 1982 election and the 2022 election, representing the South Australian Division of the Liberal Party of Australia. Lucas served as the Treasurer of South Australia between 2018 and 2022 in the Marshall government, and previously served in the role between 1997 and 2002 in the Olsen and Kerin governments. Lucas was the Father of the Parliament until his retirement at the 2022 election.

The Legislative Council, or upper house, is one of the two chambers of the Parliament of South Australia. Its central purpose is to act as a house of review for legislation passed through the lower house, the House of Assembly. It sits in Parliament House in the state capital, Adelaide.