It looks like the deadly DC comic villain Ra's al Ghul will return for Arrow's upcoming fourth season. This time, however, it will be Malcolm Merlyn - who took over the role of Ra's al Ghul at the end of season 3 - going up against Team Arrow as presumably one of the villains in season 4.

Actor John Barrowman, who plays Malcolm Merlyn on the hit CW series, recently announced that he's been finalised for the show's upcoming season.

"We start filming in July, Season Four -- I just finalized my deal about a week ago," Barrowman told an audience at the Amazing Las Vegas Comic Con held from 19 June to 21 June. (via ComicBook)

"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."

Barrowman might be hinting at some major TV crossovers as new seasons of Arrow and The Flash return this fall along with the series premiere of Legends Of Tomorrow and Supergirl.

You can watch Barrowman's comic con appearance below: