Despite the official names National Comics and National Periodical Publications, the logo "Superman-DC" was used throughout the line, and the company known colloquially as DC Comics for years before the official adoption of that name.

The company began to aggressively move against imitators for copyright violations by other companies, such as Fox Comics' Wonder Man, which according to court testimony was created as a copy of Superman. This extended to DC suing Fawcett Comics for Captain Marvel, at the time comics' top-selling character. Despite the fact that parallels between Captain Marvel and Superman were more tenuous, the courts ruled that there had been substantial and deliberate copying of copyrighted material. Faced with declining sales and the prospect of bankruptcy if they lost, Fawcett capitulated in 1955 and ceased comics publication. Years later, Fawcett ironically sold the rights to Captain Marvel to DC — which in 1973 revived Captain Marvel in the new title Shazam!. featuring artwork by his creator, C. C. Beck. In the meantime, the abandoned trademark had been seized by Marvel Comics in 1967, disallowing the DC comic itself to be called that. While Captain Marvel did not recapture his old popularity, he later appeared in a Saturday morning live action TV adaptation and gained a prominent place in the mainstream continuity DC calls the DC Universe.

When the popularity of superheros faded in the late 1940s, the company focused on such genres as science fiction, Westerns, humor and Young Romance . DC also published crime and horror titles, but they were relatively tame, thus avoiding the mid-1950s backlash against such comics. A handful of the most popular superhero titles (most notably Action Comics and Detective Comics, the medium's two longest-running titles) continued publication.