Since her first appearance in 1992, Harley Quinn—eccentric sidekick to the Joker—has captured the attention of readers like few new characters have in eight decades of Batman comics. Her bubbly yet malicious persona has earned her a loyal and growing fan base as she has crossed over into television, theater, video games, and film. In this collection of new essays, contributors explore her various iterations, focusing on her origin and contexts, the implications of her abusive relationship with the Joker, her relationships with other characters, her representations across media, and the philosophic basis of her character.