Captain Marvel has an interesting history, first published by Fawcett comics before Timely Comics changed its name to Marvel Comics. Fawcett Comics was sued by DC Comics because Captain Marvel was to similar to Superman. Fawcett ceased publication of Captain Marvel. Marvel Comics decided in 1967 to publish comics using the eponymous name. Fawcett couldn’t object as they were barred from publication. DC didn’t object because it wasn’t the name they objected to.
When DC bought out Fawcett’s characters in the 1990’s they realized they couldn’t publish Captain Marvel comics under his own name as Marvel now held the trademark. Thus the DC/Fawcett character is known by the name Shazam. A really good article about this can be found here.
See the whole story here.
Vulcan Stev's Database 