(CNN) -- London, England, street artist Banksy is already famous for quite a few things: leaving painted political messages in the West Bank; displaying a live, completely painted elephant at a 2006 show in Los Angeles, California, and a sharp sense of humor.
By the time his new documentary, "Exit Through the Gift Shop," winds its way through a slow release in the United States, Banksy will be more popular than ever -- and still, no one will know who he is.
Contrary to nearly everything we know about the way celebrity is supposed to work, Banksy's identity remains as mysterious as when he first began leaving stenciled rats on the walls of London's public spaces. He spends the entirety of his documentary in disguise, leaving film critics to question whether that's even him in the film at all.
While there have been a number of attempts to unmask the artist -- a Jamaican photographer said he snapped images of Banksy when he visited the island and a reporter at U.K.'s "Guardian" newspaper said he met Banksy (or at least someone claiming to be him) -- they've been exercises in futility. This is a man who clearly doesn't want to be found and it's highly unlikely that he'll ever reveal himself, no matter how big he gets, art observers said.
"The mystery behind his identity certainly makes him more interesting, and it has created intrigue around his persona," said Heidi Lee, founder and principal of art consulting firm Heidi Lee Art Advisory. "He has built a superhero image for himself like Batman, going around the streets at night, anonymously doing good for society and never revealing his identity. It's this heroism that attracts people more than anything."
It's an image that also attracts the media. For someone who has "published books, launched huge museum exhibitions, [and] did an installation on the West Bank wall -- how could he not be known?" asked Steve Harrington, the co-author of "Street Art: New York" and co-editor of BrooklynStreetArt.com. Obviously there are people who know who Banksy is, and "at this point he's not the only one protecting his identity," Harrington said.
"He could just be this dull, middle-aged, white guy, but how sensational would that be? It serves the needs of the media as well to help him keep his anonymous status; it's more exciting this way," he said.
It may seem that Banksy has become a victim of the hype machine that he alludes to in "Exit Through the Gift Shop," but his lack of identity is what gives his notoriety its irony.
"He needs that fame in order to get the communication out as far as he can, and he's been very, very clever about keeping his face out of it," said Liz Farrelly, whom Banksy called up in the late '90s when she was working on "Scrawl," a book about street art.
More than a decade later, "He is a celebrity, whether his face is there or not," Farrelly said. "We're not going to see him in Hello! Magazine posing with his wife and kids. ... He's done a really good job of making himself totally synonymous with his art, without us knowing anything about his life."
And these days, Banksy's artwork can go for major money, Lee said.
"Banksy's paintings sell well into the six figures. I saw one of his large paintings sell at Sotheby's auction for $1.8 million in February 2008," she said. "It was a benefit auction that was heavily advertised and it was also during the market peak, which is why it fetched such an impressive price."
Last year "was a slow year due to the recession and his prices dwindled, but he still sold paintings at impressive prices," she added. " 'Sale Ends Today' sold at Sotheby's for $230,500 USD in May 2009. Speculating collectors obviously believe Banksy is one to bank on," she said.
So if it's true that Banksy's irremovable mask is part of the intrigue drawing the unwitting to his film, since "everyone loves that one of the most famous people in the world doesn't want you to know who he is," he keeps his integrity by using the attention to drive a larger conversation, said RJ Rushmore, editor of street-art website Vandalog.com.
The movie, which was a hit at Sundance, tells the story of Thierry Guetta, a Frenchman living in Los Angeles who was filming a documentary on the world of street art, including his holy grail, Banksy.
The story turns itself inside out when Banksy realizes that Guetta is less of a filmmaker and more of a crazy guy who happens to have a camera, leading Banksy to decide to piece together the footage himself. Meanwhile, Guetta shifts from being behind the camera to being behind the paint can, creating his own street art under the pseudonym Mr. Brainwash.
The film may be gaining mainstream acceptance, but it also "critiques the art world and asks if everything in it -- including Banksy ... but in particular Mr. Brainwash -- is just PR? Is it just vapid, shallow nothingness marketed to people with lots of money? It maintains that balance of Banksy on the one hand saying, 'I'm anti-establishment' but on the other hand being a part of it," Rushmore said.
As for Banksy's true identity, he could be a homeless guy who gives away all his earnings or he could be a hedge fund manager, Rushmore said. Either way, he doesn't care to know.
"No one wants to unmask Banksy. It's not in his interest and it's not in the interest of his fans," he said. "The power in Banksy's artwork comes from his anonymity."