The Clown Prince of Crime is Batman's deadliest and most unpredictable foe. Rumored to be a failed stand-up comedian turned petty criminal who fell into a vat of chemical waste that turned his skin white and his hair green while escaping from the scene of a crime, The Joker is certifiably insane. There's a totally twisted love/hate relationship for Batman operating in The Joker. Batman knows The Joker is mentally unbalanced, perhaps beyond help, but that doesn't make the end result of his actions any less deadly.
Known as The Clown prince of Crime
Weak hand-to-hand combatant
Driven by insane and irrational compulsion to meet and test self against Batman
Employs various weapons (often based on party-gag items)
Joker Venom (toxin that stretches victim’s face into Joker-like grin and causes death)