Orsett Rural District was the local government district centred on Orsett in south Essex, England from 1894 to 1936; a little of its far west is in modern Greater London. Likewise in modern terms the area is mostly east of the M25 motorway and north of the Thames Estuary. It was formed in 1894. Housing quite few residents, it gradually fell from 62.4 to 49.6 square miles. Its notable omission was Grays or Great Thurrock; Thurrock was the main successor district.