Dinas Mawddwy () is a town in the community of Mawddwy in south-east Gwynedd, north Wales. It lies within the Snowdonia National Park, but just to the east of the main A470, and consequently many visitors pass the village by. Its population is roughly 600. The village marks the junction of the unclassified road to Llanuwchllyn which climbs up through the mountains to cross Bwlch y Groes at its highest point, the second highest road pass in Wales. This minor road also provides the closest access to the mountain Aran Fawddwy and is the nearest settlement to Craig Cywarch.