The Coldfells was a region in northern Eriador, on the foothills of the Misty Mountains.
In Third Age 2930, hill-trolls from the Coldfells took captive Arador, Chieftain of the Dúnedain, and slew him. Arador's son Arathorn II succeeded him, one year before the birth of the last Chieftain.
The location of the Trollfells is never specified beyond "north of Rivendell", as it is not mentioned on any map (or anywhere else, for that matter). Circumstantial evidence suggests the Coldfells were near to or synonymous with the Ettenmoors, which is described as "the troll-fells north of Rivendell".
 Portrayal in Adaptations
2007: The Lord of the Rings Online:
- The Coldfells in the south-eastern portion of the region of the Ettenmoors where player vs player play takes place. The land has one keep called Tirith Rhaw that can be controlled by either the forces of Angmar or the Free Peoples of Middle-earth. The Free Peoples own two other locations in the area that cannot be controlled by the forces of Angmar. The non-player characters aligned with the Free Peoples are a fraction knows as the Coldfells.