Banksy is almost certainly currently the most well known graffiti artist ever. However nothing much is known publicly about the man, except that he hails from the Bristol area (England, UK), and initially made his art on that city's streets, though later became well known for works on the streets of London. He insists on trying to keep his anonymity, and manages to do this in many ways, including using his handling service called Pest Control.
Some say he took the idea for stencilling graffiti from older French graf artist Blek Le Rat, whom he has cited as a huge influence. He also has seemingly been, at least according to his nemesis, in a street art dispute with fellow early London-based British graf artist King Robbo, although Banksy himself has never commented to affirm this, and says he has never even met Robbo.
Banksy's popularity started to escalate from the early 2000's, when he switched from freehand to stencilling, in a bid not to get caught by the Police, as stencil designs could be done much quicker than full freehand graffiti work. With humorous images, sometimes including slogans, he struck a cord with many both inside and outside the art world.
As well as working on street works around the world, he has also had many popular international exhibitions featuring gallery works on canvas and suchlike. Gaining much respect and notoriety, many of his works have been bought by the famous –notably Brad Pitt & Angelina Jolie– and both his gallery works and even some of his street works (which have often been removed from their original street positions by the building owners!) garner very high prices at auction. This is usually following official validation by Banksy himself, due to the amount of forgeries known to exist, though some have said that for a laugh he may have also validated some fakes he thought were worthwhile.
Many of his street pieces have become so well known, that many UK councils have even gone to the trouble of covering them in protective plastic to stop vandalism. Though many of his works are often the target for other taggers, with some being cleaned-up by councils, and others being covered and therefore lost completely — both usually much to the amusement of Banksy himself, who has often commented about his own over-popularity!
He has also featured in film, well kind-of...
2009 saw a spoof fly-on-the-wall TV programme called "Banksy's Coming To Dinner", where an actor pretending to be Banksy goes to a dinner party hosted by the real Joan Collins. In 2010 he released a documentary feature film, "Exit Through The Gift Shop", about his various exploits in the world of graffiti, which was nominated for Best Documentary Feature at the 2010 Oscars.