Cley Hill (grid reference ST838449) is a prominent hill to the west of Warminster in Wiltshire, England. The land is in Corsley parish and is owned by the National Trust.
A 26.6-hectare (66-acre) area of chalk grassland at Cley Hill was notified as a biological Site of Special Scientific Interest in 1975. The land is managed by the National Trust, having been gifted to the charity in 1954 by the 6th Marquess of Bath.
Archaeological features include a large univallate Iron Age hill fort, two bowl barrows and medieval strip lynchets.
There is a legend that the hill was formed by the devil, when he dropped a sack of earth with which he had planned to bury the town of Devizes. He had retrieved the earth from Somerset and was travelling to Devizes when he stopped to ask an old man the distance to the town. The man replied that he had been walking for years to reach Devizes, so the devil abandoned his plan.
Coordinates: 51°12′11″N 2°14′00″W / 51.20308°N 2.23326°W