St Harmon (Welsh: Llanarmon) is a village and community in Radnorshire, Powys, Wales.

[1] It is located on the Afon Marteg on the B4518 road running between Llanidloes and Rhayader.

The parish church is called Saint Garmon (Germanus of Auxerre), with many people assuming it has been spelt incorrectly.

St Garmon's Church is known for having the diarist the Reverend Francis Kilvert serve as Vicar there between 1876 and 1877.

St Harmon FC is the village football team.