Pen y Castell is a summit in the Carneddau mountains in north Wales. It tops the east ridge of Drum (Wales). The summit consists of rocky outcrops amid a small boggy plateau. Views of the higher Carneddau ridge to the west, Craig Eigiau to the south, Tal y Fan to the north and the Conwy valley to the east can be seen.
- ^ Nuttall, John & Anne (1999). The Mountains of England & Wales - Volume 1: Wales (2nd edition ed.). Milnthorpe, Cumbria: Cicerone. ISBN 1-85284-304-7.
Coordinates: 53°12′25″N 3°56′09″W / 53.20682°N 3.93595°W