In Scandinavia Santa Claus is kind of an immigrant. Even though he looks like it on the images he does not carry that much weight. Nisser on the other hand are everywhere.
If you should explain to an Englishman what a nisse is, you would sometimes say that a nisse is like a gnome. But there are no gnomes in Scandinavia. Gnomes are creatures of the modern romanticism (as is the lithography below), while a nisse (or sometimes tompte in Swedish) is an ancient creature living in the houses helping out or not helping according to the sacrifices he gets. I think I read that the Nisse is like the Goblin in England, but that the puritan Brits made the Goblin into something demonic, while the Nisse just stayed the homely though unpredictable pagan house-god in Scandinavia.
I had a Brit asking if the nisse was something like the house elves in Harry Potter, but this is not the case. The house elves in Harry Potter are servants, while the nisse is never a servant. On the contrary. People are supposed to keep the nisse happy with offerings of food, beer and other goodies. Else he tend to be nasty. So especially when it is JUL (Christmas) the nisse needs attention and it is custom to put rice porridge and beer on the attic for him. I have known quite a few Muslim kids committing the terrible sin of shirk sacrificing rice-porridge to the nisse in Kindergarten.
You might read some more about the Nisse on wikipedia
