Pontllanfraith (Welsh: Pontllan-fraith) is a large village and community located in the Sirhowy Valley in Caerphilly county borough, Wales, within the historic boundaries of Monmouthshire. It is situated adjacent to the town of Blackwood, with the Sirhowy River passing through both locations. The village includes the communities of the Penllwyn, Springfield, Woodfieldside and The Bryn. The population of the community at the 2011 census was 8,552.
In 1912, at the 17th-century mill in Gelligroes, amateur wireless operator Artie Moore picked up a distress signal from the RMS Titanic using wireless receiving equipment.
Pontllanfraith was a passenger station on the Taff Vale Extension of the Newport, Abergavenny and Hereford Railway from 1862. The various junctions around the station gave it access to both the Rhymney Railway and the Rumney Railway. The railway closed to most freight traffic on 9 June 1958, and the station was later demolished.
Pontllanfraith Rugby Football Club run a number of teams, with the first fifteen playing their home matches at Islwyn Park. The club has been in existence for many years and the first entry on the captain's board relates to the season 1958-59. Ponllanfraith Diamonds Cycle Club founded by Roland Morgan in 1958, which spawned a number of successful cyclists until it disbanded in 1968.
Famous people from Pontllanfraith include James Dean Bradfield (the lead singer of Manic Street Preachers) and Julian Hodge, founder of the Bank of Wales. Neil Kinnock, the Labour politician, also had a house in the village. Roy Hughes, Baron Islwyn of Casnewydd, was born there.