When Time magazine selected the British artist 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 organization 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.”

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The Barton Hill district of Bristol in the 1980s was a scary part of town. Very white—probably no more than three black families had somehow ended up there—working-class, run-down and unwelcoming to strangers. So when Banksy, who came from a much leafier part of town, decided to go make his first foray there, he was nervous. “My dad was badly beaten up there as a kid,” he told fellow graffiti artist and author Felix Braun. He was trying out names at the time, sometimes signing himself Robin Banx, although this soon evolved into Banksy. The shortened moniker may have demonstrated less of the gangsters’ “robbing banks” cachet, but it was more memorable—and easier to write on a wall.

Around this time, he also settled on his distinctive stencil approach to graffiti. When he was 18, he once wrote, he was painting a train with a gang of mates when the British Transport Police showed up and everyone ran. “The rest of my mates made it to the car,” Banksy recalled, “and disappeared so I spent over an hour hidden under a dumper truck with engine oil leaking all over me. As I lay there listening to the cops on the tracks, I realized I had to cut my painting time in half or give it up altogether. I was staring straight up at the stenciled plate on the bottom of the fuel tank when I realized I could just copy that style and make each letter three feet high.” But he also told his friend, author Tristan Manco: “As soon as I cut my first stencil I could feel the power there. I also like the political edge. All graffiti is low-level dissent, but stencils have an extra history. They’ve been used to start revolutions and to stop wars.”

The people—and the apes and rats—he drew in these early days have a strange, primitive feel to them. My favorite is a piece that greets you when you enter the Pierced Up tattoo parlor in Bristol. The wall painting depicts giant wasps (with television sets strapped on as additional weapons) divebombing a tempting bunch of flowers in a vase. Parlor manager Maryanne Kemp recalls Banksy’s marathon painting session: “It was an all-nighter.”

By 1999, he was headed to London. He was also beginning to retreat into anonymity. Evading the authorities was one explanation—Banksy “has issues with the cops.” But he also discovered that anonymity created its own invaluable buzz. As his street art appeared in cities across Britain, comparisons to Jean-Michel Basquiat and Keith Haring began circulating.

Banksy’s first London exhibition, so to speak, took place in Rivington Street in 2001, when he and fellow street artists convened in a tunnel near a pub. “We hung up some decorators’ signs nicked off a building site,” he later wrote, “and painted the walls white wearing overalls. We got the artwork up in 25 minutes and held an opening party later that week with beers and some hip-hop pumping out of the back of a Transit van. About 500 people turned up to an opening which had cost almost nothing to set up.”

In July 2003, Banksy mounted “Turf War,” his breakthrough exhibition. Staged in a former warehouse in Hackney, the show dazzled the London art scene with its carnival-atmosphere display, which featured a live heifer, its hide embellished with a portrait of Andy Warhol, as well as Queen Elizabeth II in the guise of a chimpanzee.

Late that year, a tall, bearded figure in a dark overcoat, scarf and floppy hat strolled into Tate Britain clutching a large paper bag. He made his way to Room 7 on the second level. He then dug out his own picture, an unsigned oil painting of a rural scene he had found in a London street market. Across the canvas, which he had titled Crimewatch UK Has Ruined the Countryside for All of Us, he had stenciled blue-and-white police crime-scene tape.

During the next 17 months, always in disguise, Banksy brought his own brand of prankster performance art to major museums, including the Louvre. There, he succeeded in installing an image of the Mona Lisa plastered with a smiley-face sticker. In New York City, he surreptitiously attached a small portrait of a woman (which he had found and modified to depict the subject wearing a gas mask) to a wall in the Metropolitan Museum of Art. The museum took it in stride: “I think it’s fair to say,” spokeswoman Elyse Topalian told the New York Times, “it would take more than a piece of Scotch tape to get a work of art into the Met.”

Banksy became an international star in 2005. In August, he arrived in Israel, where he painted a series of images on the West Bank’s concrete wall, part of the barrier built to try to stop suicide bombers. Images of a girl clutching balloons as she is transported to the top of a wall; two stenciled children with bucket and spade dreaming of a beach; and a boy with a ladder propped against the wall were poignant meditations on the theme of escape.

Two months after returning from Israel, Banksy’s London exhibition “Crude Oils” took the art of the subversive mash-up to new heights—Claude Monet’s Water Lilies reworked to include trash and shopping carts floating among lily pads; a street hooligan smashing the window depicted in a reimagining of Edward Hopper’s Night Hawks. A signature Banksy touch included 164 rats—live rats—skittering around the gallery and testing critics’ mettle.

There was an inevitability to Banksy’s incursion into Los Angeles with the show “Barely Legal” in September 2006. “Hollywood,” he once said, “is a town where they honor their heroes by writing their names on the pavement to be walked on by fat people and peed on by dogs. It seemed like a great place to come and be ambitious.” Crowds of 30,000 or so, among them Brad Pitt, were in attendance. “[Banksy] does all this and he stays anonymous,” Pitt told the LA Times, almost wistfully. “I think that’s great.”

The exhibition centerpiece was an 8,000-pound live elephant, slathered in red paint and overlaid with a fleur-de-lis pattern. L.A.’s outspoken animal-rights advocates were incensed; the authorities ordered the paint to be washed off. Fliers distributed to the glittering crowd made the point that “There’s an elephant in the room...20 billion people live below the poverty line.”

In February 2008, seven months before the collapse of Lehman Brothers, New York’s rich and famous gathered at Sotheby’s for a night of serious spending. The event, organized by Bono, artist Damien Hirst, Sotheby’s and the Gagosian Gallery, turned out to be the biggest charity art auction ever, raising $42.5 million to support AIDS programs in Africa.

Banksy’s Ruined Landscape, a pastoral scene with the slogan “This is not a photo opportunity” pasted across it, sold for $385,000. A Vandalized Phone Box, an actual British phone booth bent nearly 90 degrees and bleeding red paint where a pick­ax had pierced it, commanded $605,000. Three years later the buyer was revealed to be Mark Getty, grandson of J. Paul Getty.

Banksy took on the medium of film in Exit Through the Gift Shop, an antic, sideways 2010 documentary on the creation and marketing of street art. The New York Times described it as paralleling Banksy’s best work: “a trompe l’oeil: a film that looks like a documentary but feels like a monumental con.” It was short-listed for an Oscar in the 2010 documentary category.

When the Museum of Contemporary Art, Los Angeles put on its comprehensive survey of street art and graffiti in 2011, Banksy was well represented in the field of 50 artists. The show was a high-profile demonstration of the phenomenon that has come to be known as the “Banksy effect”—the artist’s astounding success in bringing urban, outsider art into the cultural, and increasingly profitable, mainstream.

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 neighborhood-revival organization. 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 Banksyan twist occurs: The locations of this street art remain undisclosed. Somewhere in London, a pair of new Banksys await discovery.