There's a killer lurking the streets of Starling City, and Oliver Queen needs to put a stop to him. Or her. See, that's the thing: we're not sure who it is.

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Ollie's

@IGN @CW_Arrow Somebody Sara knew. I still think it could be Thea.



— Chase D. Troutner (@Captain_Strongo) November 19, 2014

The

@IGN @CW_Arrow possibly a past enemy who Sara ran afoul of with the League



— A.B. (@aeb__88) November 19, 2014

Beware

More

@IGN @CW_Arrow Thea Queen. She's training to hunt down members of Team Arrow, not knowing it's her brother. Should have told her!



— Coop Cooper (@SalvaDeBoer) November 19, 2014

Oh,

After racking our brains, we came up with a few theories. Not content with some educated guesses, we wanted to get your opinion. So, we went on Twitter and asked: Who do you think the killer is? Here's what you had to say:Thea Queen and Ra's al Ghul are the strongest contenders for being the Starling City killer. Who do you think the killer is? Let us know in the comments below. Then tell us who your favorite character is this season in Arrow. Enjoy tonight's episode!

Chris Abbott is IGN's Community Coordinator. He loves loves video games, vinyl, film, burritos, and caffeine. If you love those things too, you should probably follow him on Twitter.