Actor Neal McDonough confirmed he will appear on both The Flash and Legends of Tomorrow this season as Arrow big bad Damien Darhk. The guest roles were mentioned during an interview between McDonough and ComicBook.com. The CW later confirmed the news.
McDonough brought the upcoming appearances while discussing the flashback scenes from Arrow:
You go back to the League - I did an episode of Legends last week - and I look exactly the same in 1975 but you see he's not as confident and doesn't have such an agenda forty years ago as he does now. So it's fun to play the different times, you know? Going back in time with Legends, and The Flash, with The Flash, I'm just this crazy, fun, enjoy everything while I kill everybody type of character.
Fans already know that Legends of Tomorrow will involve time travel, and the full extent of Darhk's powers has yet to be explored on Arrow, so it's unclear how the events of Legends of Tomorrow will impact those of current day Arrow. Vandal Savage is set to be the big bad in Legends' first season, and it would be interesting to see if Darhk's story ties in with Savage's. After all, they are two of DC's most well known evil, immortal beings. McDonough seemed to tease the connection. He said that he enjoyed playing Darhk throughout the years because "it's not Savage's time, it's not Ra's al Ghul's time; it's Damien Darhk's time." That sounds incredibly terrifying.
The Flash airs on The CW on Tuesday nights.Arrow airs on Wednesdays. Legends of Tomorrow is scheduled to debut in 2016.