Knudsen is a viking, and leader of his clan. He appears in the season 2 episode "Chapter 4: The Eternal Warriors", and the tie-in novel "Hilda and the White Woff". His role is the same in both continuities. The character does not appear in the graphic novels.
Knudsen has a thick, brown beard and long brown hair that he wears in a tail. He is quite big and strong in build.
In battle, he wields a magic axe that glows with red light. He might be ambidextrous, since he can be seen wielding his axe just as easily with his left hand after his right hand is chopped off.
Knudsen is quite arrogant and ruthless, though this could very well be due to the influence of the Medallion of Sigurd.
Along with his clan, Knudsen came to the Forest of Nott several centuries ago to find the Medallion of Sigurd, which would forever take away their fears. They found it, but the original owner, Sigurd, trapped them in an eternal battle with their rivals, Torgund's clan. Each night, the clan that had the medaillion would get killed by the other, after which Sigurd would revive them and the fight continued the night after. Neither side realized this due to the potion also wiping their memories of the last fight.
Early in "Chapter 4: The Eternal Warriors", they are the ones who have the Medallion, and once again get killed by Torgund and his clan. This time however, David, Frida and Hilda see how Sigurd revives Knudsen and his clan. The night after, Knudsen and his clan kill Torgund's clan and reclaim the Medallion. They are last seen departing with their loot. This was the last battle however since Hilda convinved Sigurd to stop, meaning that in the end Knudsen got the Medallion. It is unknow what became of him and his clan aferwards.