Gender in speculative fiction
The first known female superhero is writer-artist Fletcher Hanks's minor character Fantomah, an ageless, ancient Egyptian woman in the modern day who could transform into a skull-faced creature with superpowers to fight evil; she debuted in 1940 in Fiction Houses "Jungle Comics".
Superwoman
A new Superwoman named Laurel, apparently a female version of Superman from a parallel Earth (now identified as Earth-11), appeared for the first time in "Superman/Batman", and was featured an issue later. In Earth 11's alternate universe, much like in the one featured in "The Turnabout Trap!", reversed-gender characters exist relative to that resident on New Earth: there is a Batwoman (female Batman), Superlad (male Supergirl), and a female Darkseid known as the "Dark Queen". (It is notable that in pre-Crisis continuity, "Laurel Kent" was the name of a 30th-century descendant of Superman who occasionally appeared in stories featuring the Legion of Super-Heroes, and was replaced in continuity by Laurel Gand.)