If you took at look at the set photos, you've probably known for a while now that Laurel Lance would be the one to die in tonight's episode of Arrow, and die the Black Canary did after being stabbed in the chest by Damien Darhk. If reports about the hero showing up in Justice League are accurate, that's more than likely why we'll no longer see Katie Cassidy in the series, but executive producer Marc Guggenheim offered up this explanation to the DC Comics website as to why the decision was made.

"Arrow is always evolving. It’s a show where every character, arguably except for Oliver, is fair game. We started off this year with the promise of a death, and when we worked our way through our creative choices, we realized that the thing that will give us the most pop going into the end of the season and next season, unfortunately, would be Laurel. We knew that it would enrage a lot of people. We’re not blind to the “shipping” and the internet controversy, but we’ve never made decisions on the show creatively because of the internet. One of the things we knew that people would think is that in a season where Oliver and Felicity get engaged and Laurel dies, that’s clearly making a choice about who’s going to end up with whom. Truth be told, we told the Laurel/Oliver romance story in Season 1. We never really thought about going back to it."