A fascinating blog entry by Marvel Comics Executive Editor Tom Brevoort ("Things I Learned From Stan") discusses, among other things, the proper spellings of superhero and supervillain. It apparently depends on whether you work at Marvel or at DC:
4) SUPER HERO IS TWO WORDS; SUPER-VILLAIN IS TWO WORDS WITH A DASH. This all goes back to the joint trademark that Marvel and DC have on the terms super hero and super-villain—in their case, it's super-hero and super villain. (The one exception is Marvel Super-Heroes, which was trademarked as a title with the dash still in place.) Why? Because that's the way the trademark applications were filled out way back in the '70s. And as a conclusion to the Mark Gruenwald mantra by which I learned all this, superhuman is one word.
I guess it's the copy editor in me that finds this fascinating.