Cranmore Castle is an Iron Age earthwork[1] situated on a hillside above the Devon town of Tiverton in south-west England.

The earthwork is widely described in guidebooks and histories as an Iron Age hill fort[1] though more recent archaeological evaluations and histories, such as Mike Sampson's recently published work,[2] point out that it seems inefficient as a fortification, since it is overlooked from the south by the higher slope of Exeter Hill/Newtes Hill.

The Ordnance Survey Map of Southern Britain in the Iron Age[5] shows Cranmore as the largest enclosure in Devon (along with Hillsborough) at over 15 acres (61,000 m2).

During the Prayer Book Rebellion of 1549 Cranmore Castle became the site of a fierce battle fought between the two sides over whether a child should be baptised according to the 'new' religion or the 'old'.

The archbishop at the time of the Prayer Book Rebellion was Thomas Cranmer so it is possible it derives from a variation of 'Cranmer Castle' in reference to the battle fought there.