Claim: Mary Marvel was created by a science fiction author.

Mary Marvel is a fictional character originally published by Fawcett Comics and now owned by DC Comics . Created by Otto Binder and Marc Swayze , she first appeared in Captain Marvel Adventures # 18 -LRB- cover-dated Dec. 1942 -RRB- . The character is a member of the Marvel/Shazam Family of heroes associated with the superhero Shazam/Captain Marvel .   She is the alter ego of teenager Mary Batson -LRB- adopted name Mary Bromfield -RRB- , twin sister of Captain Marvel 's alter-ego , Billy Batson . Like her brother , Mary has been granted the power of the wizard Shazam , and has but to speak the wizard 's name to be transformed into the superpowered Mary Marvel . Mary Marvel was one of the first female spin-offs of a major male superhero , and predates the introduction of Superman 's female cousin Supergirl -LRB- also created by Otto Binder -RRB- by more than a decade .   Following DC 's licensing of the Marvel Family characters in 1972 , Mary Marvel began appearing in DC Comics , co-starring in DC series such as Shazam ! -LRB- 1973-1978 -RRB- and The Power of Shazam ! -LRB- 1995-1999 -RRB- . Two limited series from 2007-2009 , Countdown and Final Crisis , feature an evil version of Mary Marvel having acquired powers from first Shazam Family archenemy Black Adam and further from Apokoliptian supervillain god Desaad . In current continuity following DC 's 2011 New 52 reboot , Mary Bromfield appears as one of Billy Batson 's foster siblings , and can share Billy 's power at his whim to become an adult superhero similar to the traditional Mary Marvel -LRB- the `` Marvel '' monikers having been retired with the reboot -RRB- .