Brecon Cathedral, in the town of Brecon, Powys, is the cathedral of the Diocese of Swansea and Brecon in the Church in Wales and seat of the Bishop of Swansea and Brecon. Previously the church of Brecon Priory and then the Parish Church of St John the Evangelist, it became Brecon Cathedral following the disestablishment of the Church in Wales in 1920 and the creation of the diocese in 1923.

Brecon, archaically known as Brecknock, is a market town in Powys, mid Wales. In 1841, it had a population of 5,701. The population in 2001 was 7,901, increasing to 8,250 at the 2011 census. Historically it was the county town of Brecknockshire (Breconshire); although its role as such was eclipsed with the formation of the County of Powys, it remains an important local centre. Brecon is the third-largest town in Powys, after Newtown and Ystradgynlais. It lies north of the Brecon Beacons mountain range, but is just within the Brecon Beacons National Park.