Warner Bros. has plans to make Margot Robbie's Harley Quinn a huge part of the future of the DC Extended Universe, but with so many different films involving the character in some stage of development, we don't know for sure which one will be next.
In an interview with Collider, Robbie mentioned that we can expect to see her back in clown makeup soon, saying:
"I think we’re very close, actually. Everyone has been working really hard, myself included, to get Harley back on screen. I think it will be quite soon. There’s so much more to explore with her. I can’t wait! I hope next year, but with bigger films, it takes a lot longer to get it all up and running."
While there are plans to release Gotham City Sirens, a solo Harley Quinn movie, and a sequel to Suicide Squad, it seems like Suicide Squad 2 will be the first one to come out.
Robbie said she hasn't yet sat down with Suicide Squad 2 director Gavin O'Connor to talk about details, but there have been rumors that the film will shoot in 2018.
Even still, there are plenty of details that are still up in the air. Rumor has it that Dwayne Johnson will make his debut as Black Adam in the movie, and it is uncertain whether Jared Leto will return as the Joker. What direction the film takes with the Joker will likely have a big impact on Harley's future appearances on screen, but no matter what happens there, it looks like Robbie has a long future ahead of her in the DC Universe.