The Black Mountain (Welsh: Y Mynydd Du) is a mountain range in Mid and West Wales, forming the westernmost range of the Brecon Beacons National Park. Its highest point is Fan Brycheiniog (802 metres).
The range stretches approximately from Ammanford in the south-west to Sennybridge in the north-east, and consists mostly of Old Red Sandstone and Limestone. It is part of the recently-created Fforest Fawr Geopark.
The Black Mountain should not be confused with the Black Mountains in the east of the National Park, nor with a 702 metre summit in the Black Mountains that is confusingly also called Black Mountain.