The Artful Dodger is one of the most famous and memorable characters in the novel... and it's not because he has the coolest street name in all of London.
He provides comic relief in part because of his anti-establishment, devil-may-care attitude, but also because of the odd juxtapositions of opposites that he provides. He can’t be more than twelve, but he acts like a full-grown man, and even wears men’s clothes (with the sleeves rolled way up: suave). He talks and walks like a man, and the contrast between his attitude and his size is pretty funny. He also is one of the main "canters" of the novel—he speaks almost entirely in thieves’ cant, which gives Dickens a chance to show off what he knows, and gives the reader the titillating impression that he or she is glimpsing some authentic view of the criminal underworld.
Some critics think that the Artful Dodger is based on the historical robber and prison-breaker, Jack Sheppard. It’s possible, especially given that Dickens’s friend William Harrison Ainsworth was writing a novel about Jack Sheppard at the same time that Dickens was working on Oliver Twist.