Ra's al Ghul will return for Arrow's upcoming fourth season.

No, not Matt Nable's version; his storyline is likely finished. Malcolm Merlyn, who took over the role of Ra's al Ghul at the end of Season Three, just finalized his deal to return in the fall.

"We start filming in July, Season Four -- I just finalized my deal about a week ago," Barrowman told an audience at Amazing Las Vegas Comic Con this weekend. "I'm very excited about going back, I can't tell you anything because I do know a bit about what's going to happen. But if you love Malcolm Merlyn, if you love Oliver Queen, if you love Thea Queen, if you love the Canary sisters, and I say that with a bit of a twist and a joke in it, you're going to love what's going to happen across the DC world."

You can see the video below.

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