Pen Llithrig y Wrach is a mountain peak in Snowdonia, North Wales. It is one of the four Marilyns that make up the Carneddau range. To the east is Creigiau Gleision, another Marilyn, while to the west is Pen yr Helgi Du and Carnedd Llewelyn. Craig Eigiau and Llyn Eigiau can be seen to the north, while Gallt yr Ogof, Glyder Fach and Tryfan can be viewed to the south. It is an outlier of the Carneddau, the higher peaks of which can be reached from Pen Llithrig y Wrach via Pen yr Helgi Du. On its eastern side, the mountain slopes steeply down to Llyn Cowlyd.