The moorland to the north and west of Rivendell, in which the River Hoarwell rose. As its name suggests, this region was known to be Troll-country, and its landscape was so rocky that riding was made impossible. The Troll-fells' main entry into history was at the time of the overthrow of Angmar. When the Witch-king fled southwards, it was in the region of these fells that he disappeared.