Josiah Thomas (28 April 1863 – 5 February 1933) was an Australian politician. He was elected to the House of Representatives at the inaugural 1901 federal election, representing the Labor Party. Thomas served as a minister in Andrew Fisher's first two governments, as Postmaster-General (1908–1909, 1910–1911) and Minister for External Affairs (1911–1913). He joined the Nationalist Party after the 1916 Labor split and transferred to the Senate at the 1917 election, serving as a Senator for New South Wales from 1917 to 1923 and from 1925 to 1929.