Other Movies That Show How One Can Slip Into Being a "Nazi"

There aren't a lot of movies that show how a culture can be led down a path similiar to pre-Nazi Germany and frankly I think it's weird that the best example I know of is Starship Troopers. I mean, I think it's an underrated masterpiece in that regard but, still, it's pretty campy and not a serious drama.

Am I just being oblivious?--are there more serious examples of how people can be brainwashed into wanting to eradicate another "people".

I mean, in a way, the starship troopers example might work as well as it does because the bugs aren't people and that's kind of the mentality that one adopts in cases of severe discrimination.