Most heroes who've been around long enough manage to collect an extensive rogues gallery, but oftentimes they have just one or two primary villains who serve as their main antagonist. Superman actually has quite a few villains, but Lex Luthor overshadows pretty much all of them because his relationship to the Man of Steel is the most interesting. Same deal with the Fantastic Four and Doctor Doom, or Daredevil and Kingpin. This happens with Spider-Man and Batman as well, to a much lesser extent. Their arch-nemeses will always be Norman Osborn and The Joker, but they don't always have to be front and center like some other villains. I'm not sure why that is, but there you have it.