The Joker is a character who appears in Christopher Nolan's 2008 superhero film The Dark Knight, in which he is portrayed by Heath Ledger. Based on the DC Comics supervillain of the same name, the Joker is depicted as a psychopathic criminal mastermind with a warped, sadistic sense of humor. He seeks to test how far the vigilante Batman (Christian Bale) will go to save Gotham City from descending into chaos and targets Batman's allies, including police lieutenant James Gordon (Gary Oldman) and district attorney Harvey Dent (Aaron Eckhart). The Joker embodies themes of chaos, anarchy and obsession: throughout the film, he expresses a desire to upset the social order in Gotham through crime, and defines himself by his conflict with Batman.