The short answer is yes, but like most things in the law, what you need to do to make your characters copyrightable is more complicated than it may first appear. That's because there have been several tests that have developed over the last near-century in the Second and Ninth Circuits, which has admittedly led to confusion. Below is a brief summary of each test.
The Character Delineated Test - Second Circuit
This test developed way back in 1930 in a case called Nichols v. Universal Pictures. The case concerned a 1922 play written by Anne Nichols called Abie's Irish Rose, which was about a young Jewish man who marries an Irish Catholic girl against their families' wishes. Four years later, Universal Pictures produced The Cohens and Kellys, which was about an Irish man who marries a Jewish women, with both families disapproving. Nichols sued Universal Pictures for copyright infringement, arguing the film had similar plot points.
When talking about the characters in the play and film, the court stated that the less developed a character is, the less likely it can be copyrighted. This test came to be known as the "character delineated" test. Essentially your characters have to be unique. They can't be stock characters. To give you a sense of what the court meant, here are its words regarding characters:
"Nor does she fare better as to her characters. It is indeed scarcely credible that she should not have been aware of those stock figures, the low comedy Jew and Irishman. The defendant has not taken from her more than their prototypes have contained for many decades. If so, obviously so to generalize her copyright, would allow her to cover what was not original with her. But we need not 4 hold this as matter of fact, much as we might be justified. Even though we take it that she devised her figures out of her brain de novo, still the defendant was within its rights."
Essentially, allowing Nichols to copyright her characters would not allow others to use similar stock characters, which is not something the law encourages. Copyright law's intent is to progress the the arts and sciences, so allowing other authors to take stock elements of characters that have been around for centuries should be allowed.
This test was later applied in Anderson v. Stallone. Anderson wrote a treatment of Rocky IV. He met with executives at MGM and Sylvester Stallone, but nothing came to pass. Later Rocky IV was released, and Anderson claimed Stallone and MGM used his script, so he sued for copyright infringement.
As to the character portion of the lawsuit, the court stated "The Rocky characters are one of the most highly delineated group of characters in modern American cinema. The physical and emotional characteristics of Rocky Balboa and the other characters were set forth in tremendous detail in the three Rocky movies before Anderson appropriated the characters for his treatment. The interrelationships and development of Rocky, Adrian, Apollo Creed, Clubber Lang, and Paulie are central to all three movies. Rocky Balboa is such a highly delineated character that his name is the title of all four of the Rocky movies and his character has become identified with specific character traits ranging from his speaking mannerisms to his physical characteristics. This Court has no difficulty ruling as a matter of law that the Rocky characters are delineated so extensively that they are protected from bodily appropriation when taken as a group and transposed into a sequel by another author. Plaintiff has not and cannot put before this Court any evidence to rebut the defendants' showing that Rocky characters are so highly delineated that they warrant copyright protection..."If any group of movie characters is protected by copyright, surely the Rocky characters are protected from bodily appropriation into a sequel which merely builds on the relationships and characteristics which these characters developed in the first three Rocky movies. No reasonable jury could find otherwise..."
The Story Being Told Test - Ninth Circuit
A few decades after Nichols, the Ninth Circuit heard the case Warner Bros v. CBS, which held that the literary character Sam Spade was not copyrightable. It stated that a character could not be granted copyright protection unless it "constituted the story being told." In contrast, if a character is merely a “chessman in the game of telling the story," the court said it wouldn't be protected. The court believed Sam Spade was a "mere vehicle" that moved the story forward, so the character could not be copyrighted.
In the Anderson case, Stallone also won under this test. The court stated: "...the Rocky characters were so highly developed and central to the three movies made before Anderson's treatment that they 'constituted the story being told.' All three Rocky movies focused on the development and relationships of the various characters. The movies did not revolve around intricate plots or story lines. Instead, the focus of these movies was the development of the Rocky characters. The same evidence which supports the finding of delineation above is so extensive that it also warrants a finding that the Rocky characters - Rocky, Adrian, Apollo Creed, Clubber Lang, and Paulie - 'constituted the story being told' in the first three Rocky movies."
Stallone also won because Rocky was a visual character, which the court believed made him more identifiable, compared to a literary character that is wholly in the reader's mind.
The Story Being Told Test for Graphic Characters - Ninth Circuit
Before Stallone, the Ninth Circuit also heard a case Walt Disney v. Air Pirates. This case involved the admitted copying of Disney's characters in adult "counter-culture" comic books. The court said that the Disney characters were copyrighted because they were visually depicted. They distinguished Air Pirates from Sam Spade because Sam was a literary character and the Disney characters were visual. Cartoon characters have physical and conceptual qualities. Following the Air Pirates case, the visual nature is partly why Stallone won in his case as well.
Given the Sam Spade and Air Pirates cases, it may seem that it's easier to copyright visual characters than literary characters. If you're writing a graphic novel, comic book, or illustrated book, you may have an easier time copyrighting your characters because they're more identifiable to courts, due to their visual nature. If you're trying to copyright a literary character, I would make sure they're "well delineated" and "tell the story being told." Make sure the character is the main part of the action and not a "mere vehicle" for the story's progression. Courts may look at both tests, so I would make sure your character passes both tests.
Disclaimer: This article is for informational purposes only and is not legal advice nor is it intended to be legal advice. If you have a legal question, contact an attorney near you.