Llanthony Priory is a partly ruined former Augustinian priory in the secluded Vale of Ewyas, a steep sided once glaciated valley within the Black Mountains area of the Brecon Beacons National Park in Monmouthshire, south east Wales. It lies seven miles north of Abergavenny on an old road to Hay-on-Wye at Llanthony. The priory ruins lie to the west of the prominent Hatterall Ridge, a limb of the Black mountains. The main ruins are under the care of Cadw and entrance is free.
The priory is a Grade I listed building as of 1 September 1956. Within the precincts of the Priory are three other buildings with Grade I listed status: the Abbey Hotel, listed on 1 September 1956; St David's Church, listed on the same date, and Court Farm Barn, listed on 9 January in the same year.