Fox’s ‘Gotham’ has already introduced us to The Penguin, Catwoman and Poison Ivy, but there’s two prominent villains who haven't yet showed up on the Batman origin series, Harley Quinn and The Joker. While The Joker has long been teased and speculated upon, since the release of Suicide Squad fans have been left wondering wether his accomplice Harley Quinn will ever make an appearance.

 Margot Robbie as Harley Quinn in Suicide Squad Margot Robbie as Harley Quinn in Suicide Squad

Speaking at the Television Critics Association's summer press tour, executive producer John Stephens teased her possible introduction. “Perhaps not this season but in times to come,” he said. “A lot of those [DC Comics] characters, because they're in Suicide Squad, you're not going to be seeing them this season.

"We'll be seeing proto-versions of some of those characters. We'll see a proto Killer Croc version. And we'll be seeing a character, perhaps not this season but in times to come, who can be a forerunner of Harley Quinn which will be fun,” he added.

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The show’s writer have already teased The Joker, with many believing that he is killer Jerome Valeska, played by Cameron Monaghan. But so far writers are keeping quiet on wether he really is Batman's most famous nemesis.

"When you think of the Joker in the Batman cannon, obviously nobody else looms as large. We really imagined developing the myth of the Joker at the same time as we develop the myth of Batman," Stephens explained.

"We really wanted to stretch that over multiple seasons. So in the course of this year, we’re going to see how the cult of the Joker, started at the beginning of last year, is going to extend and deepen and change this year.”

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"We have these underground movements that have started to talk about Jerome and what he represented and how he's going to come back, setting the stage for perhaps, if Fox gives us a season four, hopefully we'll bring that back in a much bigger way and you'll see these other versions of the Joker myth with Jerome and with other characters.”

As for what fans can expect from season three, Stephens said: ”In season three you're really going to see how villains have taken up residence inside the city. The villains have become more and more a part of the fabric of the city of Gotham. It's less and less a police show like it was in season one. It's a natural continuation of that in season three.” ’Gotham' season three premieres on Fox September 19th.