Ysgol Gyfun Gymraeg Glantaf is a Welsh-medium coeducational secondary school in Llandaff North, a district in the north of Cardiff, Wales and is the largest of its kind in the country. The name 'Glantaf' means 'The bank of the river Taf' in Welsh. Of the three Welsh-medium secondary schools serving Cardiff, it was the first to be established (the others being Ysgol Gyfun Gymraeg Plasmawr and Ysgol Gyfun Gymraeg Bro Edern).