|"For any given male character, there is a female version of that character."|
and, as a corollary, "For any female character, there exists a male version of that character."
Some people believe that androgynous characters are the exception -- these people are blissfully ignorant of the amount of Bridget fanart porn that exists. Jesus Christ. Due to a funny habit in the English language of using 'he' and 'him' as default pronouns, there's plenty of artwork of monsters and objects that have no determinate gender that are Rule-63'd into having human-female characteristics: tits, a narrow waist, or just long hair and wearing a dress, bashfully hiding her nucleus behind a not-yet dissolved fan.
Rule63 doesn't require that the opposite-gendered versions be in porn, though that's fine too.
Here are some:
This is not a place to upload anything and everything Rule63 related; this is just for images already used on other articles. And try to keep this gallery worksafe.