Felin-fach is a community in Powys, Wales, northeast of Brecon. The community had a population of 673 as of the 2011 UK Census. It includes the villages and hamlets Llandyfaelog Tre'r-graig, Llanfilo, Tredomen, Trefeitha, Pen-isa'r-waen and Talachddu.[1]
St Bilo's Church, Llanfilo is dedicated to Saint Bilo and is a Grade I listed building, as is the Church of St Matthew at Llandefalle.