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.

Thomas was born in Camborne, Cornwall, England, the son of Josiah Thomas Sr. and Ann Rablin. He went to Mexico as a child with his father, a mine manager, and later worked in mines in Cornwall. He travelled to Australia in the mid-1880s and worked at the Barrier Range, near Broken Hill. He was appointed as a member of a royal commission on collieries in 1886 and worked as a mining captain and assayer in 1890. He married Henrietta Lee Ingleby in July 1889 and they subsequently had two sons and one daughter.^[1][2]

Thomas was elected to the executive of the Amalgamated Miners' Association (AMA) in July 1891 and became president of its Broken Hill branch in 1892. He was a member of the Defence Committee formed during the 1892 Broken Hill miners' strike. As a result of his criticism of the magistracy in relation to the arrest of eight fellow committee-members on conspiracy charges, he was dismissed as a Justice of the Peace. The mining companies refused to give him work and he had to take up labouring, although as president of the AMA, he was appointed to a New South Wales Legislative Assembly inquiry into lead poisoning at the mines in 1892.^[1]

Thomas was elected as the Labor Party member for Alma, covering part of Broken Hill in the Legislative Assembly in 1894,^[2] where he campaigned for improvements to workplace health and safety. He opposed the bills for the federation of Australia because he considered their referendums provisions inadequate.^[1]

After politics, Thomas was active as a Methodist preacher opposed to gambling, smoking and drinking and in particular supporting prohibition of alcohol. He participated in the establishment of Sydney radio station 2CH by the New South Wales Council of Churches. Thomas' first wife died in 1901 and he married her sister Clara Ingleby in 1909. One of his sons with Henrietta was killed on the Western Front during World War I. He died of heart disease in the Sydney suburb of Croydon Park. He was survived by his second wife and a son from each of his marriages.^[1]