While other superheroes powered box-office bonanzas, only Batman scored big for DC. (Even Superman didn't fly.) Diane Nelson and Geoff Johns are charged with changing that. First up: 'Green Lantern.'

The premiere for Marvel Studios' "Iron Man 2" shut down Hollywood Boulevard in May with the year's most bombastic red-carpet event, featuring fireworks, a heavy-metal soundtrack, go-go dancers and a parade of celebrities that included Robert Downey Jr., Scarlett Johansson, Mickey Rourke and Hugh Hefner. Walking through it all were two outsiders of a sort: Diane Nelson and Geoff Johns.

The industry odd couple — she previously managed the Harry Potter brand for Warner Bros. but had no experience in comics, he's a fan-favorite comic-book writer who had never worked at a studio — are the president and chief creative officer, respectively, of DC Entertainment, main comic-book rival to Marvel. Their task is to rummage through the massive DC library and finally get venerable characters such as Green Lantern, Wonder Woman, Flash and Aquaman on the silver screen for parent company Warner Bros. Their appointment, part of a restructuring of DC last September, is an implicit acknowledgment of the long dysfunctional relationship between the studio and its New York comic book unit.

Warner Bros. is counting on the pair to fly to the rescue and to do it soon — the Potter franchise, which has pulled in more than $5.3 billion at the box office, is winding down with its seventh installment this November and its finale next summer. The top Warner leadership is also frustrated that over the last decade it has been Marvel Comics characters — led by Spider-Man, the X-Men and Iron Man — who have won the hearts of moviegoers with franchises that have pulled in close to $8 billion.
For Johns, 37, who grew up in Michigan as a passionate comics fan, walking Marvel's red carpet gave him even more motivation to weave a Hollywood story for DC's characters, many of whom have a far more illustrious publishing history than Iron Man.

"You look at that success …it makes you want to achieve the same sort of thing but do it in our own way," Johns said. "They've done great things and now we want to do great things."

They will get their first test this week at Comic-Con International, the massive pop-culture expo in San Diego that has become a make-or-break showcase for the sci-fi, fantasy and superhero films that increasingly populate studio slates. They have one heroic success to build on — director Christopher Nolan's two Batman films have grossed $1.4 billion — but also the drag of this year's disastrous "Jonah Hex" and "The Losers," painful reminders that DC characters have often been cinematic kryptonite.

Nelson and Johns will coordinate everything DC-related — Johns, for instance, hinted that there may be a half-dozen or more potential television projects in pipeline, suggesting "Smallville" and "Human Target" may soon be joined on the air by other DC-based properties. There are also video games and toys, but the most scrutiny so far is on their role as catalysts for tentpole films at the studio, where film group president Jeff Robinov speaks as though the 75-year-old comic-book company is a fresh new asset.

"We're looking at DC as an untapped asset," he said, "since we need to find a way to fill some of the holes in our event movie schedule created by the end of Harry Potter."

On Saturday, in front of an expected audience of 6,500 at Comic-Con, Warner will present the first footage from "Green Lantern," which stars Ryan Reynolds and is the biggest effort by the studio to create a superhero franchise that doesn't feature Superman or Batman. The character, whose roots go back to the 1940s, is a member of an intergalactic peacekeeping force armed with rings that give them nearly unlimited powers.

"Lantern" is the first film made with the new DC team in place and Johns will be right up there on stage with director Martin Campbell, Reynolds and other cast members. Far from an interloper, Johns was an essential sounding board on matters of plot, tone, character design and visual effects, the film team said.

" 'Integrity officer' is a great way to describe him," Reynolds said. "He's quality control in terms of the source material and making sure we use it in the right way. If something doesn't sit well with Geoff, then everyone knows that's worthy of sounding an alarm."

The biggest challenge for Nelson and Johns may be merging the cultures of the Warner lot in Burbank and the offices of DC, which are in Manhattan but may soon move to L.A.

The company that would become known as DC Comics invented the comic-book superhero in the summer of 1938 with Superman. Its florid archive is deeper and includes more iconic characters than the Marvel library, but moviegoers certainly wouldn't know that over the last decade. "Superman Returns," a 2006 cinematic reboot of the world's best known superhero, was regarded within Warner as a critical and commercial disappointment. Instead of following it with a sequel, the studio is now allowing Nolan to produce a new take on the character.

Movies based on Marvel heroes, meanwhile, have grossed more than $7.2 billion worldwide in the last decade for a variety of studios, a track record that led Walt Disney Co. to buy the comic-book company last year for $4.3 billion. Marvel Studios is now an independent unit of Disney cranking out its own films.

Nelson and Johns say they're not out to copy Marvel and they view the competition as friendly and motivational. But the success of their competitor has clearly put the pressure on them from the highest levels of Warner parent company Time Warner Inc.

Nelson, 43, is accustomed to that type of intensity. As the lead executive overseeing the Potter franchise, she played a key role in successfully steering author J.K. Rowling's characters from the page into theaters, toy stores, theme parks and home-video collections. She has been tasked with replicating that success for DC characters.

Nelson's office is dotted with superhero bric-a-brac and, to pose for a newspaper photographer, she wore a retro Wonder Woman shirt and plastic ring with the Green Lantern logo. But she made no attempt to present herself as a lifelong fan; when asked what she knew about DC Comics before taking the job, she held up the ringed hand with her fingers in the shape of a zero.

However, Nelson said her distance from the mythology gives her plenty in common with the majority of moviegoers.

"It's no small challenge how few people have heard of these properties or understand their stories outside of fans of comic books," she said. "Sometimes the comic-book fans who love this stuff want us to get too precious about this stuff and if we do, we'll kill it off. We need to figure out how to evolve and grow it and bring it to more people."

Johns, meanwhile, is as deeply immersed in the DC mythology as any hard-core fan. After starting his career as an assistant to Richard Donner, director of the 1978 "Superman" film, he became one of DC's top writers, working on nearly every major character. Starting in 2008, he served on a team of DC writers who advised Robinov on sharpening his approach to comic books.

That made him a perfect fit when Warner executives started looking for a creative executive to work under Nelson. "Geoff knows how to make these characters contemporary and yet stick to their core values, which is a fantastic asset for us," said Robinov.

Among the DC properties Robinov would like to see on the big screen after "Green Lantern" and Nolan's Superman are the Flash, Wonder Woman and the Justice League, which would pull together many big-name DC superheroes into a team. If that last movie does happen on the new team's watch, it would be a wry twist because Nelson and Johns got their posts in part because of a previous Justice League movie that was killed shortly before filming was to begin in 2008. It was one of several ill-fated projects, along with a comedic take on Green Lantern set to star Jack Black and a TV show featuring Batman sidekick Robin that didn't mesh with Nolan's movies.

"In the past, there wasn't coordination or a cohesive plan for making movies out of DC characters," said Jeff Katz, a former executive at Warner sibling studio New Line Cinema who now runs film and comic production company American Original Entertainment. "It appears that Warner Bros. has realized they need a new strategy to get the maximum value from DC, which is clearly a smart decision."

Johns, who still pens comic-book scripts at night and on weekends, including Green Lantern, seems a bit startled by his ascension but also thrilled at the opportunity. He said a visit to the set of "Green Lantern" last month was the highlight of his professional life.

"To see a movie set for a character that I had spent so much time and creative energy on and to see it actually get shot, it was amazing. And more than that, I had been dreaming of seeing a Green Lantern movie since I was 8 years old."

geoff.boucher@latimes.com

ben.fritz@latimes.com