Foel Fraith is a hill in the Black Mountain in the county of Carmarthenshire, southwest Wales.

It lies within the Brecon Beacons National Park and Fforest Fawr Geopark.

To the north the subsidiary summit of Cefn y Cylchau reaches 556 feet (169 m), and to the southeast is the subsidiary summit of Carn Fadog or Cefn Carn Fadog, which reaches a height of 512 metres (1,680 ft).

[1] The hill has a split personality with its northern slopes dominated by the succession of Carboniferous Limestone rocks and its southern slopes by the Twrch Sandstone (formerly known as the 'Basal Grit') of the overlying Marros Group, but also dating from the Carboniferous period.

The Beacons Way from Abergavenny to Llangadog crosses Foel Fraith from east to west.