One of the stranger villains in Green Arrow's comic book gallery of rogues is Carrie Cutter aka Cupid. She is an obsessed fan of Green Arrow's and has pretty lethal ways of showing her affection. The character was created in the comics by series writer and producer Andrew Kreisberg along with artist David Baron, so you had to figure she'd show up eventually.
According to EW, for casting the role Arrow producers turned to Supernatural alum Amy Gumenick who played a young Mary Winchester in flashbacks on the other CW series. Gumenick is expected to appear as Cupid in the sixth and seventh episodes of the third season. New episodes of Arrow start on October 8th.