Robert Thomas Donaldson (1851 – 5 August 1936) was an Irish-born Australian politician. He was born in County Westmeath to farmer Thomas Willett Donaldson and Barbara Shafgotch. The family emigrated to Australia around 1863 and Donaldson worked as a station hand and prospector in northern and central Queensland. After a visit to Britain in 1878 he returned to Queensland to become a railway construction inspector. On 25 July 1882 he married Edith Meek in Sydney. He moved to New South Wales permanently in 1883 to become contractors manager in the construction of the Cootamundra-Gundagai railway. He settled in Tumut, where he became alderman and later mayor.