The Allt Graad (: Ugly Stream) or River Glass is a river in Easter Ross, Highland, Scotland. It is named on Ordnance Survey maps variously as Allt Graad and River Glass. It has also been known as the "Allt Grande", and the archaic Anglicization, "Aultgraad".

As of 2011, a hydro-electric scheme is under construction on the Allt Graad. This run-of-the-river