Troll

Trolls are mythical beings from Scandinavian folklore that mostly living far from humans mostly in isolated rocky terrain, caves, or mountains living either alone or in small family units and rarely ever being helpful towards humans. They are often depicted looking ugly and grotesque but some depictions have them also almost looking human as well.

They appeared in season 4 in the episode where they both hunted and terrorized friends who made an arrangement to hike up in the mountains of Norway unknowingly entering their terrain.