Waun-oer is a mountain in Snowdonia, North Wales, situated approximately four miles to the south-west of Aran Fawddwy.

It is one of the peaks in the Dyfi hills, a subgroup of the Cadair Idris group.

It is a top of Maesglase and the summit consists of a trig point that crowns an uneven grassy plateau.

It is connected to Cribin Fawr to the east and Mynydd Ceiswyn to the south.

[1] This Gwynedd location article is a stub.