The shrunken head, although not a character in the book, appears as comic relief in The Prisoner of Azkaban. The talking shrunken head hangs in the windshield of the Knight Bus, a purple triple-decker bus that provides emergency transport for the stranded witch or wizard. The shrunken head helps the bus driver, Ernie Prang, whose eyesight is so bad he requires very thick glasses. The shrunken head has a sarcastic sense of humor.