The Elan Valley (Welsh: Cwm Elan) is a river valley situated to the west of Rhayader, in Powys, Wales, sometimes known as the "Welsh Lake District". It covers 70 square miles (180 km2) of lake and countryside.
The valley contains the Elan Valley Reservoirs and Elan Village, designed by architect Herbert Tudor Buckland as part of the same scheme. Elan Village is the only purpose-built Arts and Crafts "Model Village" in Wales.
It is also famous for its picturesque scenery. Over 80% of the valley is designated as Sites of Special Scientific Interest, and a popular cycle trail, the Elan Valley Trail, makes a loop from Rhayader around the reservoirs. Part of the trail overlaps with a spur of National Cycle Route 81 (Lon Cambria).
As of 2015 it is an International Dark Sky Park.