Tregynon is a small village and community in Powys, Wales. The population of the community was 892 at the 2011 Census. It rests on the B4389 road which runs from Bettws Cedewain to New Mills. The country house Gregynog is nearby.
The village is named from the eponymous 6th-century Saint Cynon and the Parish Church, which is basically pre-Reformation but heavily "restored" in the 19th century, and is built on an oval shaped hillock of pre-historic significance, is named in his honour; there is also a Calvinistic Methodist (Presbyterian Church of Wales) Chapel called Bethany.
The nearby country house is Gregynog Hall, which dates from 1840; in the 19th century it was the seat of the Blayney (Blaenau, originally) Hanbury-Tracy families and became the centre of Welsh cultural life in the 20th century under Miss Margaret and Miss Gwendoline Davies, who had inherited the fortune of their grandfather David Davies of Llandinam. Although it is commonly thought that they made the village alcohol-free and made the local pub into the Temperance Hotel, it is a fact that the Temperance Hotel existed from at least the 1880s. They used their money and influence to promote their faith by regular Chapel attendance and encouraging this among their tenants and employees and paying for the erection of the Manse near to the Bethany Chapel and installing its organ. They gave refuge to wounded soldiers in both World Wars and established a printing press and local choir. They left their home to the university of Wales and a cultural, educational and retreat centre.