The Hatterrall Ridge (sometimes spelled Hatterall) is a ridge in the Black Mountains forming the border between Powys and Monmouthshire in Wales and Herefordshire in England. The ridge is about 10 miles (16 km) long, and is followed by the Offa's Dyke Path. On the west side of the ridge is the Vale of Ewyas, and on the east side is the Olchon Valley. The western side of the ridge falls within the Brecon Beacons National Park.
The highest point on the ridge is Black Mountain (elevation 703 m), near its northern end. Hatterrall Hill (elevation 531 m) is near the southern end of the ridge. The hill is common land grazed by sheep, ponies and cattle.
The ridge is often used for paragliding and hang gliding when the wind is from the east or east-north-east.