Harley Quinn, originally Dr. Harleen Frances Quinzel, first appeared in the Batman: The Animated Series episode "Joker's Favor" (September 11, 1992), created by Paul Dini and Bruce Timm as the Joker's enthusiastic henchwoman and girlfriend. She debuted in comics in The Batman Adventures #12 (September 1993, non-canon) and entered main DC continuity in Batman: Harley Quinn #1 (October 1999). Her signature red-and-black harlequin costume, inspired by commedia dell'arte and designed by Timm, featured a jester outfit with diamond patterns, establishing her playful yet dangerous persona as a psychiatrist manipulated into madness by the Joker.
Harley's early portrayals emphasized her abusive relationship with the Joker, but developments in series like Gotham City Sirens (2009) highlighted her friendship and eventual romantic partnership with Poison Ivy, marking her shift toward independence. The New 52 (2011) redesigned her with a red-and-blue motif and more revealing attire, aligning with Suicide Squad, but subsequent runs restored elements of her classic red-and-black scheme while exploring her anti-heroic side.
In recent years, Harley has solidified as a complex anti-hero, breaking free from the Joker, embracing her bisexuality (particularly with Ivy), and starring in solo titles that focus on redemption and chaos. As of 2025, her ongoing stories continue to blend humor, trauma, and heroism, with the red-and-black palette remaining iconic for symbolizing her origins and reclaimed identity.