| Pen y Garn | |
| Elevation M: | 611 |
| Prominence M: | 194 |
| Parent Peak: | Plynlimon |
| Listing: | Marilyn, Hewitt, Nuttall |
| Language: | Welsh |
| Location: | Ceredigion, Wales |
| Range: | Cambrian Mountains |
| Coordinates: | 52.3785°N -3.7666°W |
| Grid Ref Uk: | SN798771 |
| Topo: | OS Landranger 147 or 135 |
Pen y Garn (head of the cairn) is a mountain in the Cambrian Mountains, Mid Wales standing at 611 metres above sea level.
Pen y Garn tops a 500–600 m high plateau, which includes the controversial Cefn Croes wind farm. The summit has a very large shelter cairn hollowed out from the remains of an ancient burial cairn and a trig point. The wind turbines are very near the summit. To the north some 10 km, the whole Plynlimon range can be seen, including the summits of Y Garn, Pen Pumlumon Fawr, Pen Pumlumon Llygad-bychan and Pen Pumlumon Arwystli. 21 km to the west is the town of Aberystwyth; Drygarn Fawr lies 20 km to the SSE .[1]