Trevethin (Welsh: Trefddyn) is a community of Pontypool in Torfaen, Wales.
It is a modern suburb, built around a small village in the 1960s and '70s and is all but merged with nearby Penygarn. In 2005 it was announced that the district's local school, Trevethin Community School, was to close. Pupils were moved to Abersychan comprehensive school and West Monmouth School. The school buildings have now been demolished. Ysgol Gyfun Gwynllyw is a Welsh-medium education secondary school located in Trevethin.
Trevethin is situated in Pontypool and is on the southern most point of the Brecon Beacons National Park. Near to Trevethin are various famous landmarks including The Folly Tower and Grotto both of which were originally built by the Hanbury family during the 18th century.
Trevethin has been awarded Communities First status and has a strong partnership board.