American comic book Kane and Bill Finger created Batman, who debuted in "Detective Comics" #27 (1939). The period from the late 1930s through roughly the end of the 1940s is referred to by comic book experts as the Golden Age of comic books. It featured extremely large print-runs, with "Action Comics" and "Captain Marvel" selling over half a million copies a month each; comics provided very popular cheap entertainment during World War II especially among soldiers, but with erratic quality in stories, art, and printing. In the early 1940s over 90 percent of girls and boys from seven to seventeen read comic books.
Superhero This era saw the debut of first known female superhero, writer-artist Fletcher Hanks's 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 Fiction House's "Jungle Comic" #2 (Feb. 1940), credited to the pseudonymous "Barclay Flagg". The Invisible Scarlet O'Neil, a non-costumed character who fought crime and wartime saboteurs using the superpower of invisibility created by Russell Stamm, would debut in the eponymous syndicated newspaper comic strip a few months later on June 3, 1940. One superpowered character was portrayed as an antiheroine, a