[CMIII]

Here is the history behind the name.....

In 1940 Wilford Fawcett, C.C. Beck, and Bill Parker got together to create a "New" character for their comic books. What they were looking for was a Character to compete with Superman and Batman. Initially Ralph Daigh came up with the Idea of having 6 heroes combined into 1 man. So they developed Captain Thunder (this was originally Captain Marvels name). Due to a Trademark the name Captain Thunder could not be used, So they went with Captain Marvel. Fawcett's circulation director Roscoe Kent Fawcett decided to give an Alter ego direction this being that it should be a "Superman with the Alter Ego being a 10 - 12 year old boy". Eventually they 6 were chosen Solomon (Jewish King), Hercules (Roman God), Atlas (Greek Titan), Zeus (Greek God), Achilles (Greek Hero), Mercury (Roman God) they took the first letter of their names and you have "SHAZAM" when Billy says that he becomes the Mightiest Hero who fights the 7 deadly sins. Later Fawcett added 8 more Characters Black Adam, Mary Batson (Marvel), Tall Billy, Fat Billy, Hillbilly Billy, Captain Marvel Jr., Uncle Marvel, and Uncle Marvels daughter Darla. But in the mid 1940's DC (National Publications sued Fawcett City Comics over the Captain Marvel rights (Due to similarities of Captain Marvel and Superman) Fawcett City won but at that point Comic Book sales were declining. DC Sued again in 1951 and won the case and Cease orders were filed. Eventually Fawcett Sold the right to all the characters it owned to DC, DC Never copyrights Captain Marvel. In 1960 Marvel created a character they called Captain Marvel (Commonly called Captain Mar-Vell). In 1970 DC tried to reopen the Captain Marvel line, but Marvel had copyrighted the name Captain Marvel. So DC had to use a different title they went with "SHAZAM!" Finally DC tried to use the name Captain Thunder but nobody knew who it was and the popularity was low, Black Billy Batson phase. They returned to the Most well known version and eventually in the 2000's they changed Billy to his post as the Guarding of the Rock of Eternity and Had Freddy Freeman (Captain Marvel Jr) move up to the post of the Earths Greatest Hero named "SHAZAM!" in 2012 DC decided as part of the New 52 to include a Back up story to Justice League Featuring all the Marvels and they opted to call the Character Shazam.

As a side not Marvel comics must use the Character Captain Marvel every year or they will lose the right and DC can retake them