Tyrrau Mawr or Craig-las is a subsidiary summit of Cadair Idris in the Snowdonia National Park, in Gwynedd, northwest Wales. It lies to the west of Cyfrwy, and can be climbed by taking a west bearing from the Pony Path at Rhiw Gwredydd. Its north face is a crag, known as Craig-las. Below the crags lies Llyn Cregennen with its small island.