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".
Supergirl (Kara Zor-El)
Supergirl, from her debut onwards, became a regular backup strip in "Action Comics". She joined the Legion of Super-Heroes, like her cousin had done as a teenager, and in "Action Comics" #279 (July 1961) she was adopted by Fred and Edna Danvers, becoming "Linda Lee Danvers". Supergirl acted for three years as Superman's secret weapon, and her adventures during that time have been compared to contemporary developments in feminist thinking in work such as Betty Friedan's "The Feminine Mystique". She was at last introduced by her super-powered cousin to an unsuspecting world in "Action Comics" #285 (February 1962).