Glasgwm is a mountain in Gwynedd, Wales forming part of the Aran range in southern Snowdonia. It is one of the three Marilyns that make up the range, the others being Aran Fawddwy and Esgeiriau Gwynion. To the west is Maesglase and the Dyfi hills, while to the south-west lies Cadair Idris. To the south lies the Plynlimon range. It is high.