In the ending of "Joker," Arthur Fleck fully embraces his alter ego and transforms into the iconic Joker. His violent actions inspire a city-wide uprising against the wealthy and powerful, leading to chaos and destruction. As he dances triumphantly on a police car amidst the chaos, Joker becomes a symbol of rebellion and anarchy. In the final scene, Arthur is seen institutionalized, laughing uncontrollably, suggesting that his transformation into the Joker was both a personal liberation and a descent into madness. The film ends with uncertainty, leaving the audience to ponder the consequences of society's neglect and the power of the Joker's influence.