The Clan of the Fiery Cross radio serial put Superman against the Ku Klux Klan, with accurate portrayals of their beliefs and rituals. Exposing their rituals and practices to public scrutiny was actually the whole point of that serial — due to a man named Stetson Kennedy who was attempting to undermine the Klan by exposing their secrets.
The best part of the story? It worked. Superman essentially forced the Klan underground both in serial and real life.
