Fan Hir is a peak at the eastern end of the Black Mountain in the Brecon Beacons National Park in south Wales. It is a subsidiary summit of Fan Brycheiniog. It falls within the county of Powys and is also a part of the traditional area of Fforest Fawr. Its Welsh name means 'long peak', a fitting description, particularly if seen from the east when its steep eastern face is seen to advantage. Its flat summit is just over 760m above sea level.