The originalheld the mantle from 1940
Unknown (canonically unrevealed; sometimes given as Jack Napier in adaptations)
Powers. No superhuman powers; genius-level criminal intellect, expert chemist, master of poisons/toxins (Joker venom), unpredictable combatant
Origin
A chalk-white-faced, green-haired criminal mastermind who debuted as Batman's archenemy, the Joker emerged as a calculating yet theatrically deranged villain whose true identity and past remained deliberately shrouded in mystery from his very first appearance. His origins were left intentionally ambiguous, with even the character himself later suggesting that his history is open to interpretation.