Joker

The  Joker  is an insane murderous clown who terrorizes Gotham City, becoming Batman's archenemy.

Origin
Joker's origins are shrouded in mystery, and all that is clearly known is that he fell into a chemical vat, taking the color out of his skin, and turning his hair green. Blaming Batman  for this, as he had been trying to stop Joker's gang's robbery of Ace Chemicals at the time, Joker constantly tried to destroy Batman, though he had somewhat of a refusal to actually finish him off, because Batman is his only worthy opponent. Due to this, most of his attacks against Batman are personal, often against loved ones or other members of the Bat Family.