MADISON, Wis. - Bam! Zap! Whammo! It's a battle royale between two of the toughest heavyweights in the superhero business. The fate of the world doesn't hang in the balance, but a lot of money probably does.

Sci-fi writer Neil Gaiman and former Spider-Man artist Todd McFarlane's attorneys have been sparring for years over Gaiman's claims to a handful of characters created for McFarlane's classic Spawn series, which features a murdered CIA agent who becomes a demon.

Now Gaiman insists that McFarlane owes him for three more characters - a demon named Dark Ages Spawn and two avenging angels in thong bikinis. A federal judge in Madison has scheduled a hearing today to listen to both sides' arguments.

The long-running case underscores the tension among comics artists as they vie for rights to even minor characters in an industry that has grown more lucrative over the past 20 years through movies, graphic novels and international distribution.

Comic book sales totaled about $429 million last year, up from $360 million to $400 million in 1996, according to estimates by The Comics Chronicles, which compiles comic sales data. The Batman movie sequel, "The Dark Knight," has grossed over $1 billion worldwide since it was released in 2008, according to Box Office Mojo.

Spawn isn't nearly as popular as Batman or Spider-Man, but the series has been fairly successful with action figures, an Emmy-winning HBO series and a 1997 movie that grossed $87 million worldwide. A sequel is in development, according to Image Comics' Web site.

Gaiman's attorneys said that Gaiman plans to donate any money that comes out of the case to charity. The lawsuit for him is more about establishing clear guidelines for other comic-book creators about their rights to characters, they said.

"Our view is, McFarlane just took some of the characters Neil was a co-creator of and just gave them different names," said Gaiman's attorney, Allen Arntsen. "It's a matter of principle."

McFarlane's lead attorney, James Alex Grimsley, didn't return several messages seeking comment. In court filings, though, McFarlane's legal team denied that Gaiman has any right to the three additional characters, arguing that they're based on ideas from the Spawn universe, not other characters.