Mister J is a fictional character often associated with the DC Comics universe, primarily known as the Joker. He is depicted as a chaotic and unpredictable villain, frequently opposing the superhero Batman. Mister J is characterized by his clown-like appearance, complete with white skin, green hair, and a wide red smile. In various adaptations, Mister J is portrayed as a master manipulator and criminal mastermind. His antics often involve elaborate schemes and a dark sense of humor, making him one of the most iconic villains in comic book history. His complex relationship with Harley Quinn adds depth to his character.