Madness is the emergency exit. You can just step outside, and close the door on all those dreadful things that happened. You can lock them away... forever.
The Joker is a supervillain and the archenemy of Batman. The Joker is a master criminal with a clown-like appearance. The Joker is a vicious, calculating, psychopathic killer. The Joker has been responsible for numerous tragedies in Batman's life, including the paralysis of Barbara Gordon (Batgirl/Oracle) and the murders of Jason Todd (the second Robin) and Jim Gordon's second wife Sarah.