In a couple of decades, Harley Quinn went from being a popular supporting character for Batman's top antagonist to being a popular character that exists independently from the Joker. Harley's progression, at least in the narrative, has been circuitous, but her rise outside the fictional realm has been meteoric. Even though the first Suicide Squad movie had a disastrous critical reception, fans were so thrilled with Margot Robbie's turn as Harley Quinn that the character was granted a spin-off.
In addition to her various movie outings, Harley has quietly been behind one of the most consistently hysterical offerings from the adult animation world. HBO Max's Harley Quinn, starring the Big Bang Theory's Kaley Cuoco as the titular character, is easily one of the smartest superhero shows on any platform, with blisteringly funny gags that take aim at virtually every beloved character in DC's extensive roster. The trailer linked above showcases footage from Harley Quinn's upcoming third season.