Suicide Squad is out now to many of the critics Margot Robbie's Harley Quinn steals the show (sorry, Jared Leto). Check out our review, where we concur.
And more than that – it looks like she's set to get her own solo film, which feels like a complete no-brainer to us.
Harley has become one of Batman's most popular villains since she first appeared in the '90s, and has a surprisingly complex and tragic backstory. Here's everything you need to know to get you up to speed:
A Mad Love
Harley has a unique origin for a comic book character in that she wasn't originally a comic book character at all. She was first seen in Paul Dini and Bruce Timm's much-loved Batman: The Animated Series in the 1992 episode 'The Joker's Favor' as one of the titular villain's henchpeople, dressed in a harlequin outfit and sporting a piercing New York accent courtesy of actress Arleen Sorkin.
She proved so popular she was made into a recurring character, who frequently found herself kicked out by 'Mister J'. On one such occasion she became friends with Poison Ivy - another pairing that would recur throughout her history.
Her origin was revealed in Dini and Timm's Eisner Award-winning 1994 comic The Batman Adventures: Mad Love. Harley Quinn was Dr Harleen Quinzel (seriously), a psychiatrist interning at Arkham Asylum who fell in love with the Joker which - professional ethics aside - is not something a sane person is likely to do.
The story was adapted for TV in a New Batman Adventures episode, also called 'Mad Love'.
Queen of Crime
Harley has been a staple of comics ever since, with as much focus placed on her relationship with Ivy as on her dysfunctional Joker team-ups. She has regularly appeared in Batman and its sister title Detective Comics.
She was popular enough to receive an ongoing solo series in the early 2000s, and later starred in Gotham City Sirens with Poison Ivy and Catwoman.
DC's New 52 reboot introduced a new take on Quinn that was far from universally loved. She swapped her all-in-one harlequin suit and hood for pigtails and a skimpy outfit that - were we feeling particularly harsh - we might compare to a demented spring breaker. This is the look the filmmakers have gone with.
The New 52 also saw Harley's inclusion in the latest comic book version of the Suicide Squad, the government-sponsored black ops team of supervillains. She is also starring in another new Harley Quinn series which has proved to be a huge hit.
On top of all this, Harley has become a staple of the Arkham games, appearing in all four (including a take on her origin in Batman: Arkham Origins).
Tragic love
The popularity of Harley Quinn is probably due to the fact that she seems simple but is in reality a deeply troubled and tragic figure.
Harley is on the surface a whimsical and loveable sort of character (for an insane supervillain), with her jester outfit, exaggerated accent and tendency for bumbling.
But under the veneer of fun is a woman who is in love with a monster. Harley is obsessed with the Joker, who was responsible for her transformation in the first place. But the Joker is a psychopath, and his sole obsession is Batman. Harley is a useful tool to him at best, at worst an annoyance to be thrown away.
That's what is so painful and fascinating about her character. Whatever cute, goofy or evil act she does for love and attention, she will never get either.
Whether Robbie's character will embody these deep psychological issues remains to be seen. So far, all we can say is that we're loving her acrobatics.
Where to start
The Batman Adventures: Mad Love
Harley Quinn creators Paul Dini and Bruce Timm unite to tell the tragic origin of Harleen Quinzel.
Harlequinade
This episode of Batman: The Animated Series is classic Harley and Joker with a MUSICAL NUMBER thrown in for good measure.
Batman: Harley and Ivy
Dini and Timm deliver hilarious and remarkably touching tales spotlighting DC's oddest couple.
Harley Quinn: Hot in the City
A new direction for Harley in the New 52, away from the Joker and out on her own, with stellar work from Amanda Conner and Jimmy Palmiotti.
