Garreg Las is a subsidiary summit of Fan Brycheiniog in the Brecon Beacons National Park (Parc Cenedlaethol Bannau Brycheiniog) in Carmarthenshire, southern Wales. Its summit sits towards the northern end of a broad north-south ridge, Esgair Hir (long ridge), at above sea level. The hill is sometimes referred to as Twyn Swnd.