Albert "Jupp" Gardiner was an Australian politician who served as a Senator for New South Wales from 1910 to 1926 and again briefly in 1928. A member of the Labor Party, he served in cabinet as Vice-President of the Executive Council under Andrew Fisher and Billy Hughes, and from 1916 to 1926 was his party's Senate leader; he was its only senator from 1920 to 1922. Before entering federal politics he had served in the Parliament of New South Wales from 1891 to 1895 and from 1904 to 1907.

The Leader of the Opposition in the Senate is a party office held by the Opposition's most senior member of the Shadow Cabinet in the Australian Senate, elected to lead the opposition party in the body. Though the leader in the Senate does not have the power of the office of Leader of the Opposition, there are some parallels between the latter's status in the lower house and the former's in the Senate. In addition to his or her own shadow ministerial portfolio, the leader has overarching responsibility for all policy areas and acts as the opposition's principal spokesperson in the upper house. The leader is entitled to sit at the table of the Senate, and has priority in gaining recognition from the President of the Senate to speak in debate. Another similarity is that the leader typically announces changes to opposition officeholders in the Senate, including shadow ministers, party leadership and whips. The leader also has some responsibility for appointing opposition senators to committees, a role filled by the Manager of Opposition Business and whips in the lower house. The current leader is Simon Birmingham. He is assisted by a Deputy Leader of the Opposition in the Senate, currently Michaelia Cash.