Stac Rhos is a top of Pen y Boncyn Trefeilw in north east Wales.

It forms a part of the Berwyn range called the Hirnantau.

The views from the summit are extensive, if unremarkable due to the featureless, flat moorland surroundings.

The summit is marked by a small cairn, and a boundary stone.

To the east is Cyrniau Nod, while Cefn Gwyntog is to the south-east.