Glyder Fawr is a mountain in Snowdonia, Wales, the highest in the Glyderau at just over 1,000m. It is the fifth highest mountain in Wales.
The summit lies on the ridge between Glyder Fach and Y Garn, and has views to the north, across the Ogwen Valley, of Pen yr Ole Wen and the Carneddau, and views south to the Snowdon Horseshoe. The summit plateau is very rocky, making progress slow.
Routes to the summit start at Ogwen Cottage on the shores of Llyn Idwal to the north, from Pen-y-Pass to the south, and along the Glyder ridge to the east. One of the most popular routes from Ogwen Cottage follows the shore of Llyn Idwal to the base of the famous Idwal Slabs (a popular rock climbing crag), it then makes its way out of the cwm via the steep Devil's Kitchen path, arriving at a small lake called Llyn Y Cwn. From here a steep scree path ascends the western shoulder to the summit of Glyder Fawr.
Until late-2010, most maps showed a height of 999m for Glyder Fawr, however it was resurveyed with accurate GPS equipment and found to be 1,000.8m.
The summit marks the boundary of Gwynedd and Conwy County Borough.
According to Sir Ifor Williams, the word "Glyder" derives from the Welsh word "Gludair", meaning a heap of stones.