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) adversaries in Modern Age comic book stories. The two are often portrayed as equally matched and, while Marvel does not possess Superman's heat vision, X-ray vision or superhuman breath powers, the magic-based nature of his own powers are a weakness for Superman. The National Comics/Fawcett Comics rivalry was parodied in "Superduperman", a satirical comic book story by Harvey Kurtzman and Wally Wood in the fourth issue of "Mad" (April/May 1953). Superduperman, endowed with muscles on muscles, does battle with Captain Marbles, a Captain Marvel caricature. Marbles' magic word is "SHAZOOM", which stands for Strength, Health, Aptitude, Zeal, Ox (power of),