Thornbury Rural District was a rural district council centred on Thornbury in the south of Gloucestershire. It was originally formed as a Poor Law Union on 5 April 1836 with 26 Guardians representing the 21 parishes in the Union and the Guardians of the Poor became the Rural Sanitary Authority for the District in 1872. The Rural District Council became a separate body in 1894 although the District Councillors had a dual mandate as members of both the council and the Board of Guardians.The District was enlarged in 1904 when Henbury was transferred from the abolished Barton Regis District.