Glyder Fawr is a mountain in Snowdonia, Wales, the highest in the Glyderau. It 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 is very rocky, making progress slow. A notable feature east of the summit is Castell Y Gwynt, "the castle of the wind", a spiky rocky outcrop. Routes to the summit lead from Ogwen Cottage on the shores of the lake Llyn Idwal to the north, from Pen-y-Pass to the south, and along the Glyder ridge to the east and west, leading to Y Garn and Glyder Fach.
The summit marks the boundary of Gwynedd and Conwy County Borough.
"Castell y Gwynt" and the "Cantilever Stone" were used in Walt Disney's The Dragonslayer, this was one entrance to the Dragon's lair.