Batman dominates comic book sales on eBay

A man reaches for a Batman comic book at a comics store in New York.
Shannon Stapleton | Reuters

Marvel's Avengers may rule the box office, but DC's Batman is king of e-commerce.

Comic book collectors are notorious for seeking out prized issues, and the Dark Knight is top of the list for treasure hunters on eBay. In the last six months, shoppers on the site shelled out $4.7 million on Batman comics, according to an analysis by market research firm Terapeak. (Tweet This)

And the contest wasn't even close. The second-place Avengers came up short by a margin of $1.7 million.

Read More Can Marvel claim victory in the TV hero onslaught?

This was not the first time Terapeak has studied superhero sales. Last year, it issued a report on which superheroes move the most comics, toys, costumes and other merchandise on eBay—and Gotham's favorite son came out on top in that report, too.

"The first time we did this about a year and a half ago, I think we were surprised Batman towered above everyone else in terms of eBay sales," said Aron Hsiao, data scientist at Terapeak. "We thought it would cool off."

Hsiao and his team figured the caped crusader might be riding high on the buzz around the 2012 film "The Dark Knight Rises" when they first ran the numbers, but at 76 years old, Batman remains a spry moneymaker.

Terapeak decided to focus on comic book sales after eBay promoted its comics marketplace last month by asking Reddit users to weigh in on 20 superhero grudge matches. The firm wanted to see how those 40 superheroes stacked up in dollars and cents, so it gathered data on auctions over the last 180 days to find out what collectors were searching for and how they were spending.

Since eBay selected the characters thematically, some high earners may not be represented. But the list includes most of Marvel and DC's best-known heroes and villains.

While searches that began with Batman brought home the championship for DC Comics, Marvel character queries took all but two of the top 10 spots. (Superman was No. 5.)

Read MoreThe most valuable comic books of all time

"Earth's Mightiest Heroes" proved a formidable force, indeed. The Avengers and four members of the team featured in the blockbuster movie—Hulk, Iron Man, Thor and Captain America—placed in the top tier. (Wolverine and Spider-Man, who have also been card-carrying Avengers in the comics, took Nos. 4 and 6, respectively.)

The team trend did not hold for DC; sales linked to Batman, Superman, the Flash (No. 12), Green Lantern (No. 13), and Wonder Woman (No. 14) all topped receipts for the team to which they belong, Justice League (No. 16).

Whether that will change once the Justice League makes its big screen debut in next year's "Batman v Superman: Dawn of Justice" remains to be seen.

One surprise winner in the contest: Marvel antihero Deadpool. With more than $1.2 million in eBay sales, the cult character beat out many of DC's heavy-hitters. That would seem to bode well for actor Ryan Reynolds, who will star in a live-action Deadpool movie next year after pushing the project for years.

Read More New deal brings Disney blockbuster hits to Imax

The vast majority of sales scraped by Terapeak's algorithms came from comic book auctions, though some pieces of memorabilia were counted. The auction items also ranged from spendy collector's issues to dollar-bin discount books.

"It's a really interesting market and category because it goes from very, very accessible prices to ... the realm of pristine, archetypal issues that are the stuff that kids and collectors dream about," Hsiao said.