Ulfric Stormcloak, easy. Hitler. Supreme race (Nords)
There is no evidence that he believes this, or that his rebellion has anything to do with some kind of Nordic "racial supremacy."
has managed to conceal his racism with the reasoning that "Skyrim belongs to the Nords"
This might be relevant if it actually were a Stormcloak rallying cry, but unfortunately for people who like to use it as "evidence" of something uniquely nefarious with regard to Ulfric, it's not. It's something Nords say. NORDS. Not Stormcloaks. Bandits say it, members of the Companions - many of whom will tell you they don't give a damn about the war - say it, your housecarls will say it if you take them into battle, hunters chasing (presumably non-Nord) deer through the woods say it.