Glascwm is a civil parish in the upper Edw valley in Powys, Wales. The main settlement is concentrated in the two centrally located small villages of Frank's Bridge, located on the eastern slope of the valley, and Hundred House, located on the river terrace on the western side of the Edw. The remainder of the population lives in scattered farms and dwellings and in the three rural settlements of Cregrina, Glascwm and Llansantffraed-in-Elwel. The surrounding area has extensive uninhabited uplands of moorland at Carneddau, Gilwern Hill, Gwaunceste Hill, Little Hill and Glascwm Hill. The A481 passes through the area. In 2005 Powys county council recorded a population of 479, increasing to 551 at the 2011 Census.