Fan Hir is a peak at the eastern end of the Black Mountain (Y Mynydd Du) in the Brecon Beacons National Park (Parc Cenedlaethol Bannau Brycheiniog) in southern 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. It is about 2.5 miles or 4 km long and faces east. Its summit is 2490 feet (about 760m) above sea level. Fan Hir is separated from its higher neighbour to the north-west, Fan Brycheiniog (2633 feet or 802 metres) by a col known as Bwlch Giedd, where a path rises from Llyn y Fan Fawr via a stone staircase.