Nazi Germany is a minor character in the comic. The most important thing to understand about him is that he is not Germany. His relation to Germany, if any, is unknown, even if Germany does feel the guilt over Nazi Germany's actions. Other than that, Nazi Germany is exactly what you would think--a viciously racist, creepy wannabe dictator who somehow persists into the modern day even though his regime was toppled well over 60 years ago. He still hangs on to the treasure he looted from other countries in those days (while refusing to give it back), and relishes the prospect of another world war. He is the closest thing the strip has to a proper villain.
He is one of only two ghost characters, which represent places which no longer exist (although he could still represent modern neo-nazism, or even Germany's guilt). The other being Atlantis. Although Prussia has appeared in SatW, the comic he was in was based when he was alive, so he has yet to appear as a ghost.
Scandinavia: Nazi Germany loves the Scandinavians, especially Denmark. They're his kind of people. Unsurprisingly, they find this very disturbing. Back when he was on his world rampage, they weren't sure how to react--he was obviously evil, but he didn't seem to bear them any particular ill will and they didn't know whether it was worth making him angry by resisting. Sweden went into denial about the whole thing, and Denmark made only a token resistance, hoping it would all blow over soon. Only Norway really stood up to Nazi Germany.
Family: Nazi Germany is presumably related to Germany and Sister Germany in some way, but it has never been specified. Germany seems to feel responsible for the way Nazi Germany behaves, and it appalls him.
The World: As if everyone who has ever taken a history course or looked at any form of fiction doesn't know - Nazi Germany is feared and hated by all (except presumably Fascist Italy and Imperial Japan, but they never appeared in the comic).
Nazi Germany looks sort-of-but-not-really like Adolf Hitler, with sickly pale skin, shadowy eyes, and black hair with a severe left-side part. The lower part of his head is shaved. He wears a long-sleeved collared shirt with the design of the Nazi flag. In his first appearance, he wore round wire-rimmed glasses, but in subsequent comics he wears a pince-nez. Almost the only facial expression he ever displays is a scheming smile, and the little heart that appears over his head when he is pleased is black and angular--even his affection is tainted with his evil.
- "I love your pretty pale skin, and your golden hair is to die for."
- "Sie Feligling! Haben Sie kein Dorn! Standplatz gerade! Stoppen Sie zu schreien! Sie sind pathetisch!"
- "World War 3, here I come!"
- He was not tagged for his appearance in "Swedish Politics".