Colin Donnell returning to guest star in Arrow season 6

Chicago Med’s Colin Donnell will revisit his role as Tommy Merlyn in an upcoming Arrow season 6 episode, returning to the CW series for another guest spot.

While Colin Donnell stars on Chicago Med, fans will soon be able to watch him return to another of his best-known TV roles.

Stephen Amell posted a photo on Twitter that confirms Donnell is appearing in an Arrow season 6 episode, though details about his guest appearance are still unknown.

The sixth season of Arrow is currently airing and runs through May 17, so One Chicago fans won’t have to wait long to see Donnell’s guest spot.

He was a series regular during Arrow season 1 as Tommy Merlyn, the best friend of Amell’s Oliver Queen. The two of them competed over Oliver’s ex-girlfriend Laurel Lance (Katie Cassidy), whom Tommy ultimately died trying to save in the first season finale.

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But though Tommy is dead, Colin Donnell has continued to return to the series in a variety of ways. He appeared in flashbacks and visions in seasons 2 and 3, and recently surprised fans by turning up as an alternate-universe evil version of Tommy Merlyn in November’s “Crisis on Earth-X” crossover event.

A hologram version of Tommy was also seen in the show’s 100th episode in 2016, when Donnell wasn’t available due to his Chicago Med filming schedule. (A caveat that Arrow acknowledged wonderfully by saying that copy of Tommy had become a successful doctor in Chicago.)

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So how will Colin Donnell come back to Arrow this time?

Amell’s Tweet doesn’t say anything explicitly, but does mention the previous flashbacks, which would seem to make the most sense given that Tommy is deceased. Unless, of course, we’re going to see a third alternate version of the character—but getting back to the real, still missed Tommy Merlyn would be more rewarding.

However it happens, getting to watch Colin Donnell reprise a great character and enjoy him in a role other than Dr. Connor Rhodes will be fun for Chicago Med fans. We’ll keep you posted when we have more information on his Arrow episode; until then, see Stephen Amell’s tweet below and you can watch Arrow season 1 through reruns on TNT.

Next: Read our latest interview with Colin Donnell

How do you think Colin Donnell will return in Arrow season 6? Will you be tuning in when he does? Tell us your thoughts in the comments, and don’t miss him in a new Chicago Med tomorrow night.

Chicago Med airs Tuesdays at 10/9c on NBC.