The Cambrian Mountains (Welsh: Mynyddoedd Cambria, in a narrower sense: Elenydd) are a series of mountain ranges in Wales. The term Cambrian Mountains used to apply to most of the upland of Wales. Since the 1950s, its application has become increasingly localised to the geographically homogeneous Mid Wales uplands, known in Welsh as Elenydd, which extend from Pumlumon to Radnor Forest in the east and Mynydd Mallaen to the south. This barren and sparsely populated 'wilderness' has been referred to as the Desert of Wales. The area includes the sources of the River Severn and River Wye and was unsuccessfully proposed as a national park in the 1960s and 1970s. The highest point of the range is Plynlimon, at 2,467 feet (752 m).

The wider, more historic, use of the term also includes Snowdonia in North Wales, and the Brecon Beacons and Black Mountains in South Wales. They range in height up to 3,559 feet (1,085 m) in Snowdonia.