The Glogn ( Romansh, ) is a whitewater river in Graubünden. Glenner was also the name of a district in this area, which was annexed by Surselva District in 2001.
The river rises near the border with Ticino and is surrounded by up tp 3100m high mountains. The river flows through the Val Lumnezia. In Suraua, the Vals Rhine flows into the Glogn. After a few more kilometers, the Glogn flows into the Vorderrhein at Ilanz. In the upper reaches of the river has cut a deep gorge, which has uncovered black shale in a few places. During the snow melt and after rains the river water is usually dark gray.