The Joker is a character portrayed by Heath Ledger and the main antagonist in Christopher Nolan's 2008 superhero film The Dark Knight. Based on the DC Comics supervillain of the same name, he is depicted as a psychopathic criminal mastermind with a warped, sadistic sense of humor who defines himself by his conflict with the vigilante Batman. In the film, the Joker tests how far Batman will go to save Gotham City from descending into chaos. He targets Batman's allies, including police lieutenant James Gordon and district attorney Harvey Dent, to prove that no one is incorruptible.