Last season, Harley Quinn popped up in Arrow for a brief cameo appearance, with Cassidy Alexa portraying the character on screen and Tara Strong supplying her voice [you can watch the scene here]. During an interview with Comic Book Resources, Arrow executive producer Andrew Kreisberg was asked about the chances of Harley returning to The CW series, but judging from his response it seems that Warner Bros. could have other plans for the DC fan favourite.
“I don’t know [if we’ll see Harley again]. There are very few things we’ve asked DC Comics for that we haven’t gotten. That was something you asked for, and what you saw is a compromise that Geoff Johns and I came up with. To even get that much was a thrill for us. I know that they may have other plans for her, but it was certainly an Easter egg that thrilled us. But the Suicide Squad will definitely be back. Whether we see the ‘deranged female killer’ we saw before, we’ll have to wait and see.”
As for what these other plans might entail, there have been rumours of a potential Suicide Squad movie, but it seems unlikely that would prevent Harley from appearing in Arrow, seeing as there’s no issue with the rest of the team. Beyond that, an appearance in a solo Batman movie is certainly not beyond the realms of possibility, but with Batman v Superman not arriving until 2016, that would seem to be quite a way off at present. Still, with Harley one of DC’s most popular characters, it’s surely a given that we’ll be seeing her on the big screen at some point.
