Margot Robbie is currently working on a solo Harley Quinn movie as well as the previously announced spinoff film.
"I've been working on it for two years now." said Robbie. "It's hard to kind of talk about it because all this stuff is under lock and key, but no I've been working on a separate spinoff Harley thing for a while now... [Not Sirens], it's a totally separate one. Yeah, there's a lot going on right now and I honestly don't think anyone knows what's gonna be the next thing to happen, but I think everyone's keen to get Harley back on screen so everyone's working on different versions of what that could be."