Theophilus Martin "Theo" Nicholls (21 August 1894 – 22 July 1977) was an Australian politician. Born in Wilmington, South Australia, he received a primary education before becoming a wharf labourer. He served in the military 1915-1917, was secretary of several unions including the Manufacturing Grocers' Employees Federation and the Wool and Basil Workers Federation[1]. He was active in a number of labour movement organisations, such as South Australian Trades and Labour Council, and was vice-president of the South Australian Labor Party. In 1943 he was elected to the Australian Senate as a Labor Senator for South Australia. He held the seat until his retirement in 1967. Nicholls died in 1977. His nephew, Martin Nicholls, was a Labor MP for Bonython 1963-1977.[2]