Pen Llithrig y Wrach ('Slippery Head/Top of the Witch') is a mountain peak in Snowdonia, North Wales.

To the east is Creigiau Gleision, another Marilyn, while to the west are Pen yr Helgi Du and Carnedd Llewelyn.

It has one of the more colourful names of any British mountain, translating as slippery peak of the witch, perhaps in reference to the boggy conditions underfoot, or because of the resemblance of its pointed profile to an archetypal witch's hat.

On its eastern side, the mountain slopes steeply down to Llyn Cowlyd.

It may be climbed from the southern side, from Capel Curig or the A5, or from the north-east, from Dolgarrog or Tal-y-bont in the Conwy valley.