(Bloomberg) -- The original cover art for the 1986 graphic novel Batman: The Dark Knight Returns will be offered for sale on June 16 with a $2 million estimate at Heritage Auctions in New York.

The four-issue miniseries, written by Frank Miller, is widely credited for pivoting Batman from hokey children’s fare to a more sophisticated and sinister form of storytelling. Everything from Tim Burton’s brooding, charmingly weird 1989 Batman movie, to Zack Snyder’s similarly brooding but singularly leaden 2021 Justice League, can be traced back to Miller’s story.

“I was in the throes of penciling up the first issue of The Dark Knight Returns, and I was hunting around in my mind for a single image that would sum up the entire series,” says Miller, in a phone interview. “I knew that I really wanted it to stand out, and I looked around at all the other [comic book] covers and they were all just cluttered with endless superhero figures scrambling all over each other, with tons of detail.”

Instead, he created an image of Batman in silhouette, illuminated by a single lightning bolt that cuts across the page. “As soon as I penciled down the lightning bolt, I knew I had a really good idea,” Miller says. “It’s like whispering when everyone else is shouting.” (The original image is ink over graphite, with airbrush color work.)

The series was an immediate, runaway success. The first printing quickly sold out, Miller says, and the comic eventually had two print runs. “It became a real cause for celebration,” he says. “I was getting calls from all over the place from stores that had run out of copies the first day they got it.”

Over time its reputation grew, to the extent that in 2009 Time magazine ranked it as one of the top 10 graphic novels, ever. Miller, meanwhile, went on to create other critically acclaimed series including Sin City and 300.

The painting, co-created by Miller and colorist Lynn Varley, remained in Varley’s possession, Miller says, until she sold it through an intermediary in 2013. “To answer your implicit question here,” he says, “nobody had any idea how much it would be worth.”

Market Growth

For a while, it wasn’t worth that much. “Honestly, the value was so low, for so long, that a lot of it got thrown out,” says Todd Hignite, a vice president at Heritage Auctions, of comic book art. “There’s not a history of treating it with the same reverence that fine art would be.”

And yet in the past few years, along with a range of collectible markets including baseball cards and sneakers, the comic book market has skyrocketed, with particularly rare examples selling for millions of dollars. In 2019, for instance, before the market’s pandemic boost, Heritage sold a piece of original comic book art, Frank Frazetta’s Egyptian Queen from 1969, for $5.4 million. Although recent numbers haven’t quite reached that level, the volume of million-dollar sales is on the rise.

In April 2021, a copy of the 1938 Action Comics #1, where Superman made his debut, sold for $3.25 million via ComicConnect. A few months later, Heritage sold the first Spider-Man comic (Amazing Fantasy No. 15) in near-perfect condition for $3.6 million. This past January, a single page of artwork from the 1984 comic Secret Wars No. 8, where Spidey’s black suit first makes an appearance, sold for $3.36 million.

Meanwhile, “certain covers have traded privately for approaching a million dollars,” Hignite says. Within that context, he continues, the $2 million estimate “is a reasonable expectation, and if anything, conservative.”

Enduring Impact

Bidders, Hignite says, keep getting younger. Much like the classic car market, where people who grew up in the 1980s suddenly have the cash to invest in their nostalgia, comic book buyers are ready to collect totems of their youth.

“The bidder pool is just getting deeper and deeper, and wider and wider,” he says. “In every auction, I used to look at the top 20 lots we’d sell, and I’d immediately recognize 90% of the names. That’s not the case anymore.”

When Captain America’s introductory comic book sold for $3.12 million at Heritage last month, “it was a buyer who’d never bought anything from us before,” Hignite says. “It’s a completely changing world.”

For Miller, who isn’t consigning the work and doesn’t have a financial stake in its success, the multimillion-dollar estimate is proof of the comic book’s enduring impact. “If you’re talking about the Dark Knight project, it’s self evident that it’s formed the approach to how characters are treated in today’s comics and movies,” he says. “The character needed to be toughened up and darkened up.”

©2022 Bloomberg L.P.