Neal McDonough has joined Arrow's fourth season as Damien Darhk, The CW announced Friday.

Darhk is a former adversary of Ra's Al Ghul who now leads his own clandestine group and will prove to be one of Oliver's (Stephen Amell) biggest challenges. He first appeared in Starling City in Season 3, but was never seen onscreen. Now, the Captain America: The First Avenger alum will bring this mysterious, sophisticated villain to life when Arrow returns on Wednesday, Oct. 7 at 8/7c.

Could Darhk be the reason that Oliver and Felicity must return to Starling City?

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