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
Captain Marvel (DC Comics) low-print run in the fall of 1939 as an ashcan copy created for advertising and trademark purposes. Shortly after its printing, however, Fawcett found it could not trademark "Captain Thunder", "Flash Comics", or "Thrill Comics", because all three names were already in use. Consequently, the book was renamed "Whiz Comics", and Fawcett artist Pete Costanza suggested changing Captain Thunder's name to "Captain Marvelous", which the editors shortened to "Captain Marvel". The word balloons in the story were re-lettered to label the hero of the main story as "Captain Marvel". "Whiz Comics" #2 (cover-dated Feb. 1940) was published in late 1939.