There is no doubt that Margot Robbie's Harley Quinn was the center of everyone's attention when "Suicide Squad" came out. Given this, it comes as no surprise that a spin-off movie starring the character, alongside two other Batman villainesses, is being fast-tracked for a 2018 release.

"Gotham City Sirens" is apparently the main focus on Warner Bros. right now, especially considering the critical flop that is "Suicide Squad." An all-female ensemble is definitely the trend nowadays — with the latest "Ghostbusters" and "Ocean's Eight" as examples. The upcoming Harley Quinn-led film will also see Poison Ivy and Catwoman, gathering three of Batman's most prominent female enemies.

Robbie is, of course, set to reprise her role as Harley Quinn, but Poison Ivy and Catwoman have yet to be cast. However, there is a rumor going around that Megan Fox may be playing the voluptuous Poison Ivy.

According to Bleeding Cool, Fox has apparently been ordering a lot of comic books that feature the character. Since Fox is a known comic book fan, though, this could easily be interpreted as the actress simply wanting to read the issues. Nothing can be known for sure about the casting yet, so fans should take this with a grain of salt. 

However, Ben Affleck is expected to appear in "Gotham City Sirens" in some form or another. Affleck has got a lot of films on his plate — most of them from the DC Extended Universe. "Justice League" is set to bow in 2017, with a solo film, "The Batman," scheduled for a 2018 release. Also dropping in that year is Jason Mamoa's "Aquaman" and, possibly, "Gotham City Sirens."

Another character that fans want to return is Jared Leto's Joker. It is widely known that the strange villain did not really make a big impact on "Suicide Squad," owing it to his small screen time and supporting role. It is unknown if Leto will ever want to reprise his role, especially since "Gotham City Sirens" will certainly focus on the three villainesses.