Carnedd Dafydd is a mountain peak in the Carneddau range in Snowdonia, North Wales, and is the third highest peak in Wales, or the fourth if Crib y Ddysgl on the Snowdon ridge is counted. Situated south-west of Carnedd Llewelyn and north of Pen yr Ole Wen, Carnedd Dafydd is on the main ridge of the Carneddau, and on the border between Gwynedd and Conwy.