Copyright law and trademark law are both very important to comic book creators. As an intellectual property lawyer, these are the two areas of law I deal with the most. They are also areas of law that can be easily confused, but they protect very different things.
Copyright law at its most basic level protects a creative work. It protects the way a work is written or drawn. It gives the creator of the work the right to recreate it, publish it, and create derivate works based upon it. It also prevents unauthorized uses of the work that infringe on the creator’s rights.
Trademark law serves a different purpose. A trademark is “[a] word, phrase, or logo, or other graphic symbol used by a manufacturer or seller to distinguish its product or products from those of others.” The purpose of a trademark is to identify a seller’s legitimate goods in the marketplace and to prevent consumer confusion. A trademark does not protect the title of a single creative work. However, it can protect the title of periodical publications, such as comic books. It does not protect the name of a character unless that character’s name also serves as a trademark.
A comic book series can be protected by both copyright and trademark law. The art and story in a comic book are protected by copyright law. The depictions of the characters, such as their design and character attributes, are also be protected by copyright. The title of the work is protected by trademark law.
The most prominent example of how these differing laws interact in comic book publishing is Captain Marvel. As I’ve discussed before, Fawcett introduced the character Captain Marvel in the late 1930s. After DC Comics brought a copyright infringement lawsuit against Fawcett by DC Comics, Fawcett stopped publishing the character because the court found that the character infringed on DC’s copyrights to Superman. Had Fawcett continued publishing the character, Fawcett would have been found to have committed additional copyright infringement. (Note: I still believe the decision to be incorrect, but that was what the court decided.)
Subsequently, Marvel Comics obtained a trademark registration to publish a comic book using the title Captain Marvel. Marvel Comics introduced a new character using the same name, and continued to publish comic books titled Captain Marvel. When DC Comics obtained the rights to use Fawcett’s Captain Marvel, they were prohibited from calling the book Captain Marvel due to Marvel’s ownership of the Captain Marvel trademark registration covering comic books. Hence, DC published the stories of Fawcett’s Captain Marvel character under the title Shazam!
Two characters with the same name can coexist simultaneously. If they are not copies of each other, or close imitations, then they do not violate copyright law. If the works in which they are published do not include their name, then trademark law is not a concern. However, if one character is published in a work that includes their name, such as Captain Marvel, then another publisher with a character using the same name would be prohibited from using that character’s name in their title.
Generally speaking, it is advisable to avoid using the name of a character that already exists. Even if copyright law isn’t a concern, the elements of trademark law could trip up the unwary.You might find yourself in an undesirable situation, such as a threat of a lawsuit or the inability to use your character’s name as the title of your book. As I mentioned in my Comics Startup 101 post, a clearance search is the best way to protect yourself from unwittingly running afoul of trademark law.
 Black’s Law Dictionary, 2nd Pocket Ed.