It's kind of pedantic question perhaps, or maybe if the reason I'm not getting the point is not that English is my second language, perhaps you can call it a feminist outcry, but regardless:
Why is there a space in "Wonder Woman" but none in "Superman"?
Imao, both of these are the same thing, more or less, only designed for presumably different marketing demands.
Or maybe it is just beauty of shorter words.
It's only natural that whoever creates a superhero name should get to decide whether to use a space (as in Wonder Woman) or nothing (as in Superman) between the first word and the second. Does this necessarily mean that creating a superhero name is purely arbitrary and is not bound by any rules of English? I don't think so.
Nor do I think it's got anything to do with treating 'man' differently from 'woman', because we have Superwoman, Wonder Man and Batwoman instead of Super Woman, Wonderman and Bat Woman, respectively.
I for one think that it's got to do with the length of the first word. For example, Wonder has six letters, which might feel a bit too long to combine with the following word in a single word ?Wonderwoman or ?Wonderman. Super has five letters, which might feel short enough to combine with the following word in a single word Superman or Superwoman. And Bat has only three letters, which might feel short enough to combine with the following word in a single word Batman or Batwoman.
That said, arbitrariness cannot be entirely excluded when it comes to inserting a hyphen between the two words. For example, Spider, has the same number of letters as Wonder, but Spider-Man and Spider-Woman do not have a space but a hyphen in between. A shorter word Man is also connected with Bat via a hyphen in Man-Bat.
Except for the use of a hyphen, it's got to do with the length of the first word rather than with the second word being man or woman.
It is also used to distinghuish the characters. For example:
Spider-Man’s name has a hyphen because Stan Lee, who created the comic character with Steve Ditko, apparently wanted to distinguish him from Superman.
When the character was first conceived, her proposed name was actually "Suprema - The Wonder Woman". This was replaced with simply "Wonder Woman," which was an existing term defined in the dictionary as "a woman who can be a successful wife and have a professional career at the same time" and in popular use during the 1940s at the time of her inception. So the main reason her name was a two-word term is that it was originally more of her title than her name (like Robin the Boy Wonder).
Also, it is notable that there was an acknowledged trend during the silver age of comics to give comic book characters alliterative names (eg Peter Parker, Bruce Banner, Billy Batson etc). Although Wonder Woman and Superman were from the earlier golden age of comics, DC arguably started this trend with Lois Lane and Lex Luther in Superman. Wonder Woman continued this trend, perhaps intentionally.
Had Wonder Woman been named "Wonderwoman" they would not have been able to stylise it as WW, or create the recognisable logo that incorporates the two 'W's (although this was not created at her debut and did not appear until 1982).
