The tale of Harley Quinn as a character in DC Comics is one that is known well to fans both casual and hardcore. She started out not in the comics, but in the Batman The Animated Series TV show, and was created by Paul Dini as an assistant/henchman/love interest to Joker. Eventually, she did indeed crossover to the comics, and from there she’s been in video games, cartoons, live-action TV series like Arrow (in a brief tease) and Gotham, and of course, live-action movies.
She was a part of the original Suicide Squad movie, and was the breakout star of the film as she was portrayed by Margot Robbie. Then, she went onto be in the Birds of Prey film, which despite a somewhat low box office total has a very loyal following and was critically praised by many. She’s set to be in James Gunn’s The Suicide Squad next year, but after that, it’s a bit up in the air. However, according to DCEU Mystic, Warner Bros is in talks with Robbie to get her into another film. But as to what is that film, and its role, no one is sure.
This comes hot off the heels of Henry Cavill talking with Warner Bros to be in another DCEU film despite it not being Man of Steel 2 as of yet.
Originally, the plan was for Harley and Jared Leto’s Joker to have a film together, and then give Harley her own story. But that changed into the Birds of Prey film. Most fans are still hoping for Gotham City Sirens to happen, which would pair Harley Quinn alongside long-time BFF and love Poison Ivy, as well as Catwoman. Though whether that’ll happen with The Batman coming from Matt Reeves is unclear.
That being said, it can’t be overlooked that Birds of Prey 2 would be an option, and Margot Robbie worked hard to get that movie made the way she wanted, so she would definitely be in a sequel.