Fimbulwinter - In Norse mythology, Fimbulwinter is the immediate prelude to the end of the world, Ragnarök. Fimbulwinter is three successive winters where snow comes in from all directions, without any intervening summer. During this time, there will be innumerable wars and brothers will kill brothers.
Ragnarøkkr - In Norse mythology, Ragnarök ("fate of the gods") is the battle at the end of the world. It would be waged between the gods (the Æsir, led by Odin) and their aggressors (Loftur and his monstrous children, as well as, among others, the Jötnar). Not only will some of the gods, giants, and monsters perish in this apocalyptic conflagration, but almost everything in the universe will be torn asunder.