Shortly following confirmation that Harley Quinn is being considered for the show, "Gotham" executive producer Ken Woodruff suggested the idea that the character had already arrived in earlier seasons.
"You may have already seen Harley as a person that you thought you had met and known for a long time. So we always reserve the right to sort of do that as well," he told IGN -- a revelation that took star Camren Bicondova (Selina Kyle) by surprise: "Ummm, I didn't know that!"
Executive producer John Stephens referenced Killer Croc -- who will be introduced at the beginning of Season 3 -- when he spoke about Harley Quinn. Unlike Croc, he said, "the Harley Quinn of it all is a bit more of a sticky wicket but it's one we've already thought about for the character. We don't want to give too much away but it will definitely be someone connected to the Joker cult world that we have set up. But it's down the road, later in Season 3 right now."