Montagu is a rural locality in the local government area (LGA) of Circular Head in the North-west and west LGA region of Tasmania. The locality is about north-west of the town of Smithton. The 2016 census recorded a population of 92 for the state suburb of Montagu.
Montagu was gazetted as a locality in 1967. The Montagu River and the locality were named for John Montagu, who was Colonial Secretary of Van Diemen's Land from 1834 to 1842.
The Montagu River forms the western boundary, and the waters of Robbins Passage form the northern.
Route C215 (Montagu Road) runs through from east to west.