1) Poison Ivy
If there is one of DC’s female characters who really has to appear in the movie, it’s Poison Ivy. The green-fingered villainess is usually portrayed as Harley’s best friend, particularly in the acclaimed Batman: The Animated Series for which Harley was first created.
In that show and in the comic books, it is often insinuated that Harley and Ivy are lovers – something that fans of the characters have often called to be explored further. Hopefully, a Harley Quinn film will bring this fan favourite love story to the screen in some form.
Besides that, Poison Ivy hasn’t been seen on the big screen since the campy portrayal by Uma Thurman in Batman and Robin all the way back in 1998. Given her prominence in the Dark Knight’s rogues gallery, we would pay good money (on our bat credit cards) to see this be rectified soon.