'Captain Marvel' was a Golden Age Super-hero, who was arguably Superman's greatest comic book rival during the 1940's, even surpassing him in sales at one point. He first appeared in Whiz Comics #02 (1940), published by Fawcett Comics. He was created by writer, Bill Parker and artist C.C. Beck.
His alter ego was Billy Batson, an orphaned teenage radio broadcaster and orphan. He was brought by a magic train to an underground lair, where he met the mysterious wizard 'Shazam'. The wizard gives him superpowers to combat the forces of evil. To use these powers all Billy had to do was say the wizard's name 'Shazam!'
Captain Marvel's main foe was Dr. Sivana, a mad scientist bent on world domination. Captain Marvel also fought Captain Nazi, Ibac, and the despicable Mister Mind and his Monster Society of Evil. During World War II, he even fought Adolf Hitler, Mussolini and Tojo.
Captain Marvel was assisted in his fight against crime and evil by the 'Marvel Family', which included Billy's twin sister Mary, who becomes 'Mary Marvel' when she says 'Shazam'. It also includes Freddy Freeman, who after being mortally wounded by Captain Nazi, was given the power to become Captain Marvel Jr. when he says 'Captain Marvel'.
Captain Marvel has the wisdom of Solomon, the strength of Hercules, the stamina of Atlas, the power of Zeus, the courage of Achilles, and the speed of Mercury.
The character now appears in DC Comics, who hold the trade-marks for the names 'Shazam' and 'Billy Batson', however as Marvel Comics owns the trademark for the name 'Captain Marvel' (for a different character) DC comics renamed the comic book Shazam!