Castleton is a village in the High Peak district of Derbyshire, England, at the western end of the Hope Valley on the Peakshole Water, a tributary of the River Noe, between the Dark Peak to the north and the White Peak to the south. The population was 642 at the 2011 Census.

The Peak Cavern, also known as the Devil's Arse, is one of the four show caves in Castleton, Derbyshire, England. Peakshole Water flows through and out of the cave, which has the largest cave entrance in Britain.