Stan Shunpike

Stan Shunpike is the young, pimply conductor of the Knight Bus. He speaks with a Cockney accent, and converses with Harry as he travels to London in the first part of Prisoner of Azkaban. He also appears briefly in Harry Potter and the Goblet of Fire at the Quidditch World Cup, boasting to a group of Veela, the Bulgarian team's official mascot, of his ambitious plans to become the next Minister of Magic. In Order of the Phoenix, he conducts the Knight Bus when Harry, Ron, Hermione, Fred, George, Ginny, Lupin, and Tonks take it to return to Hogwarts after the Christmas holidays. He is glad to see Harry Potter, and mentions that he does not believe the media rumours about Harry being insane. Tonks scolds him for yelling Harry's name aloud.
In Harry Potter and the Half-Blood Prince, Stan Shunpike is arrested on suspicion of Death Eater activity. Harry and Dumbledore, however, believe that he is almost certainly not guilty. Even so, Stan is kept in Azkaban in order for the Ministry of Magic to give the pretence that progress is being made in the capturing of Death Eaters. When the new Minister of Magic asks Harry to be a sort of mascot for the Ministry, Harry refuses on the grounds of the Ministry's actions at the time - namely holding Stan under arrest.
In Deathly Hallows, a "strangely blank" looking Shunpike was among the Death Eaters who pursued Harry during his escape from Privet Drive. Harry gave himself away to his attackers by attempting to only Disarm Shunpike, as Harry believed him to be under the Imperius Curse.