Here are some contenders:
* Fantomah (1940): Often cited as the first female superhero, she was a jungle woman with supernatural powers. However, she predates the modern definition of a superhero, appearing in pulp magazines rather than comics.
* Wonder Woman (1941): This iconic character is widely recognized as one of the first and most popular female superheroes. She debuted in her own comic book and quickly gained widespread recognition.
* Black Canary (1941): Debuting in a comic book in the same year as Wonder Woman, Black Canary had a distinct martial arts focus and a more grounded, human persona.
Ultimately, the answer depends on your definition of a superhero and the specific criteria you prioritize. While Fantomah might hold the title based on her earlier appearance, Wonder Woman and Black Canary are arguably the most significant and impactful female superheroes of that era.