Arendelle's Boss, the giant wolf Heartless "Skoll", is named after and based on the figure of the same name in Norse (Viking) mythology. Specifically, the Vikings believed that two wolf figures, Hati and Skoll, were in constant pursuit of the Moon and Sun in order to devour the two celestial bodies, thus creating the day and the night. Skoll can also be seen trying to darken the boss arena at times in reference to Skoll successfully devouring the Sun during the Ragnarok, the end of all of the realms of the universe in Norse mythology.