When the long-awaited first trailer for Suicide Squad was released in July 2015, two of the movie’s DC villains immediately stood out above the rest: Jared Leto’s Joker and Margot Robbie’s Harley Quinn. Since then, rumors of Leto’s questionable method acting—terrorizing his fellow cast members with used condoms and anal beads, channeling the ghost of Heath Ledger, etc.—have cooled the heat around his performance as the Joker. But the buzz around Robbie and Harley Quinn has only grown. Comic-Con 2016 was flooded with Harley Quinn cosplayers last month, and the Harley-centric Suicide Squad trailer that dropped July 20 quickly eclipsed 2 million views. Fans are practically frothing at the mouth over the sexy, mysterious, and dangerous anti-heroine.

Harley Quinn has been the favored child of the DC villain subset since her earliest beginnings. She first appeared in 1992 in "Joker's Favor," an episode of Fox's Batman: The Animated Series, written by Paul Dini and edited by the series’ co-creator Bruce Timm. Sporting a black and red jester bodysuit, a rich red mask with twin bells, and the same chalk-white face as her psychopathic love interest, she was the perfect foil to the Joker. Vivacious, alluring, and head over heels for Gotham’s biggest bad boy, Harley Quinn was an instant hit on the series. And let’s be honest: What’s badder than being the only person in the world who can make the Joker catch feelings?

After breaking out on Batman: The Animated Series​, Harley Quinn has morphed and taken on countless identities over the last two decades. She’s appeared in a bevy of comic series, animated shows, and video games with near cult-like followings. Fans initially latched on to Harley Quinn not simply because she offered the Joker's character the dimension it lacked, but because, as Harley Quinn comic series artist Chad Hardin puts it, his love for her is the "the only redeeming thing" about his character. But Harley was too interesting of a character to be left under the Joker's (often abusive) sway, so DC made the smart decision to let her branch out and drive her own series. From there she gained a following by making being bad look really, really good. And added bonus? She's out of her mind, looney-tunes insane.

To better understand the phenomenon that is Harley Quinn, Complex reached out to the men and women who know her best: her creators. The OG co-creator Paul Dini (whose graphic novel Dark Night: A True Batman Story dropped in June), along with a handful of writers and artists—among them DC Comics’ Suicide Squad writer Adam Glass, and co-writer of the ongoing Harley Quinn series Jimmy Palmiotti—led us on a deep dive into the origins of Harley and her many iterations. From her first appearance in the early '90s right up to her big role in the most anticipated blockbuster of summer '16, here's everything you need to know about DC’s most compelling antagonist.