Captain Marvel (DC Comics) abilities. Based on book sales, the character was the most popular superhero of the 1940s, outselling even Superman. Fawcett expanded the franchise to include other "Marvels", primarily Marvel Family associates Mary Marvel and Captain Marvel Jr., who can harness Billy's powers as well. Captain Marvel was also the first comic book superhero to be adapted into film, in a 1941 Republic Pictures serial titled "Adventures of Captain Marvel". Fawcett ceased publishing Captain Marvel-related comics in 1953, partly because of a copyright infringement suit from DC Comics, alleging that Captain Marvel was a copy of Superman. In 1972, DC licensed the
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.