Bwlch y Ddwyallt is the name commonly applied to the high point of the plateau of Gwaun Cerrig Llwydion in the eastern part of the Brecon Beacons in south Wales.

[1] The plateau reaches its highest point of 754 m (2,474 ft) above sea level on its northern rim overlooking the head of Cwm Cwareli.

The name is an odd one to apply to a peak since the Welsh word 'bwlch' generally signifies a col or pass between mountains.

These beds directly overlie the sandstones of the Brownstones Formation, also of Devonian age, which form the bulk of the hill.

The cliffs below Bwlch y Ddwyallt shows signs of having been glaciated during the ice ages as do those beneath Graig Fan Las on the eastern edge of the plateau.