St Harmon (Welsh: Llanarmon) is a village in Powys, Wales. The population of the community at the 2011 census was 593. It is located on the Afon Marteg on the B4518 road running between Llanidloes and Rhayader.
St Harmon FC is the village football team. The Sun Inn is the village pub.
- "Community population 2011". Retrieved 14 November 2015.