Llanddewi Ystradenni is a community in Radnorshire, Powys, Wales. The population of the Community at the 2011 census was 310.[1]
Centred on the village of Llanddewi, it also includes the hamlet of Heartsease.
The motte and bailey fortification of Buddugre Castle, overlooking the Afon Ithon, is also within the community.