Can be tamed.

Level:10-45 Elite
Name:Retains original name after taming.
Zone:Halls of Valor (Dungeon)
Location & Notes:

Located in Fields of the Eternal Hunt, Halls of Valor (Dungeon). The runes on Fenryr's flanks glow when he runs. He can only be tamed after you defeat him in Mythic mode, and only if you solo the dungeon up to, and including, that fight. That means you must also solo the first boss of the dungeon (Hymdall) as well as Fenryr. The tameable version of Fenryr spawns at the back of his den after you defeat him.