Variety of Marine Character categories.
TLDR: Marine characters are spread across numerous categories-Marines, Starfleet Marines, Marine personnel, along with some ship specific categories from some of the older ships that seemed to have been used instead of "ship x characters" or "ship x alumni". I've found quite a few categories thus far.
My intent is to put all Marine characters under Category:Marines, as that's the largest + the category recommended on the character creation guide. Also intending to make sure categories are up to date on marine characters while I'm at it.