Ystradfellte is a small village and community in southern Powys, Wales, in the historic county of Brecknockshire (Breconshire) in the Fforest Fawr area of the Brecon Beacons National Park. It lies beside the Afon Mellte. The village is linked by minor roads with Heol Senni to the north and the A4059 north of Penderyn, and with Pontneddfechan at the head of the Vale of Neath to the south.
Ystradfellte is chiefly known in Welsh history as the place where the Welsh nobleman and rebel leader Llywelyn Bren surrendered at the end of his revolt of 1316. Llywelyn gave himself up on the condition that his men be spared, but was himself put to death in 1318 at Cardiff.
The village was connected to mains electricity in 1960, one of the last communities in the whole of England and Wales to be wired. Outlying properties in the Nedd Fechan valley had to wait until December 2005 for their connection.
The village is a popular centre for tourists for its hillwalking, waterfalls and caves along the nearby rivers. Ystradfellte has a pub, the New Inn, and Croydon Caving Club. It comes under Aberdare for postal purposes.
- Porth yr Ogof, with the biggest cave entrance in Wales, into which the River Mellte flows
- Little Neath River Cave
The area is considered to be part of Waterfall Country. A popular attraction near the village is the Waterfalls Walk, an easier walk along the Afon Mellte past two main falls on the river, Sgwd Clun-gwyn and Sgwd Isaf Clun-gwyn, to Sgwd yr Eira on the Afon Hepste, where the footpath passes behind the waterfall.
- "Community population 2011". Retrieved 15 November 2015.
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- "Big switch-on as the valley time forgot leaves the dark ages". BBC News. 2 December 2005. Retrieved 8 March 2019.
- "Evan Bevan". Dictionary of Welsh Biography. National Library of Wales. Retrieved 12 April 2016.