Fenris

Fenris is a frozen little hellhole in Warhammer 40,000, most notable for being the homeworld of the Space Wolves. Named after the ancient Viking wolf monster involved in Ragnarok (because the Space Wolves are also Space Vikings, at least at first), Fenris is located in either the Segmentum Solar or the Segmentum Obscuris, and is what the Imperium politely classifies as a Death World, meaning everything on the planet is trying to kill its human inhabitants. Which makes it the ideal place to recruit an army of space vikings. Fenris is composed of a single continent called Asaheim, with hundreds of islands in its vast world sea. Those parts of Fenris which aren't completely frozen over and unable to sustain human life more than a few minutes alternate between frozen and undergoing constant earthquakes. The Fenrisian wolves are amongst the most dangerous predators in the galaxy, and they reach the size of motorcycles SMALL HORSES OR APCs! The dominant sea life are octopus things called krakens, and they have tentacles that can reach miles in length. There are also things walking about the snow of Asaheim that the locals refer to as trolls. All in all, it's one of the deadliest planets in the galaxy.

And the Space Wolves love every minute of it.