Banksy—graffiti master, painter, activist, filmmaker and all-purpose provocateur—for its list of the world’s 100 most influential people in 2010, he found himself in the company of Barack Obama, Steve Jobs and Lady Gaga. He supplied a picture of himself with a paper bag (recyclable, naturally) over his head. Most of his fans don’t really want to know who he is (and have loudly protested Fleet Street attempts to unmask him). But they do want to follow his upward tra­jectory from the outlaw spraying—or, as the argot has it, “bombing”—walls in Bristol, England, during the 1990s to the artist whose work commands hundreds of thousands of dollars in the auction houses of Britain and America. Today, he has bombed cities from Vienna to San Francisco, Barcelona to Paris and Detroit. And he has moved from graffiti on gritty urban walls to paint on canvas, conceptual sculpture and even film, with the guileful documentary Exit Through the Gift Shop, which was nominated for an Academy Award.

Pest Control, the tongue-in-cheek-titled organisation set up by the artist to authenticate the real Banksy artwork, also protects him from prying outsiders. Hiding behind a paper bag, or, more commonly, e-mail, Banksy relentlessly controls his own narrative. His last face-to-face interview took place in 2003.

While he may shelter behind a concealed identity, he advocates a direct connection between an artist and his constituency. “There’s a whole new audience out there, and it’s never been easier to sell [one’s art],” Banksy has maintained. “You don’t have to go to college, drag ’round a portfolio, mail off transparencies to snooty galleries or sleep with someone powerful, all you need now is a few ideas and a broadband connection. This is the first time the essentially bourgeois world of art has belonged to the people. We need to make it count.”

It could be said that Banksy’s subversiveness diminishes as his prices rise. He may well have reached the tipping point where his success makes it impossible for him to remain rooted in the subculture he emerged from.

The riots in the Stokes Croft area of Bristol in spring 2011 offer a cautionary tale. The episode began after police raided protesters, who were opposed to the opening of a Tesco Metro supermarket and living as squatters in a nearby apartment. The authorities later said that they took action after receiving information that the group was making petrol bombs. Banksy’s response was to produce a £5 “commemorative souvenir poster” of a “Tesco Value Petrol Bomb,” its fuse alight. The proceeds, he stated on his website, were to go to the People’s Republic of Stokes Croft, a neighbourhood-revival organisation. Banksy’s generosity was not universally welcomed. Critics denounced the artist as a “Champagne Socialist.”

He has countered this kind of charge repeatedly, for instance, telling the New Yorker by e-mail: “I give away thousands of paintings for free. I don’t think it’s possible to make art about world poverty and trouser all the cash.” (On his website, he provides high-resolution images of his work for free downloading.)

The irony, he added, that his anti-establishment art commands huge prices isn’t lost on him. “I love the way capitalism finds a place—even for its enemies. It’s definitely boom time in the discontent industry. I mean how many cakes does Michael Moore get through?”

While the value of his pieces soars, a poignancy attends some of Banksy’s creative output. A number of his works exist only in memory, or photographs. When I recently wandered in London, searching for 52 previously documented examples of Banksy’s street art, 40 works had disappeared altogether, whitewashed over or destroyed.

Fittingly, the latest chapter in the enigmatic Banksy’s saga involves an unsolved mystery. This summer, during the London Games, he posted two images of Olympic-themed pieces online—a javelin thrower lobbing a missile, and a pole vaulter soaring over a barbed-wire fence. Naturally, a Banksy twist occurs: The locations of this street art remain undisclosed. Somewhere in London, a pair of new Banksys await discovery.