Maelienydd, sometimes spelt Maeliennydd, was a cantref and lordship in east central Wales covering the area from the River Teme to Radnor Forest and the area around Llandrindod Wells. The area, which is mainly upland, is now in Powys. During the Middle Ages it was part of the region known as Rhwng Gwy a Hafren, or "Between the Wye and the Severn". Maelienydd was one of the cantrefs brought together to form Radnorshire. The name survives for the general area.