Captain Marvel (DC Comics) Comics" #21 (1941) introduced the Lieutenant Marvels: three other boys named "Billy Batson" who could also become adult superheroes. Captain Marvel, Jr., the alter-ego of disabled newsboy Freddy Freeman, debuted in "Whiz Comics" #25 (1941). Mary Marvel, alter-ego of Billy's twin sister Mary Batson, first appeared in "Captain Marvel Adventures" #18 (1942). In contrast to Captain Marvel and the Lieutenants, both Mary Marvel and Captain Marvel, Jr. remained kids in superhero form, and were given their own eponymous books in addition to appearing as the lead features in "Master Comics" and "Wow Comics", respectively. Captain Marvel, Captain Marvel Jr., and
Adventures of Captain Marvel most popular superhero, and they agreed. Director William Witney, however, was skeptical about trying to adapt Captain Marvel after the problems encountered with Superman. In spite of this, "Adventures of Captain Marvel" became the first superhero film adaptation of a comic book character. National attempted legal action to prevent Republic from developing their arch rival's most successful character, citing Republic's failure at adapting a Superman serial. Their attempt was unsuccessful, however, and Captain Marvel went into production. Writing in his autobiography of the period, William Witney revealed that in his court deposition he had claimed that both Superman and Captain