This comic is actually an adaptation of the animated Valhalla movie (though I'll say that in this case the adaptation is better than the movie).
It went like this: Peter Madsen started the Valhalla comic in 1979, starting the humorous adaptations of the old Norse myths. Three albums were made from the period 1979-1982, and then came the animated movie in 1987, adapting one of the most famous myths -- namely the trip to Utgard-Loki. This movie was then adapted into the fourth and fifth album in the series, which added quite a few extra scenes.
The fifteenth and final album is actually scheduled to come out (in Danish and Norwegian) this month. Guess who's going to get that? ^_^ (Hint: I live in Norway.)