Alex Karev was one of the few original 'Grey's Anatomy' characters left on the show. So when news emerged that the actor behind him, Justin Chambers, had left the show, fans were shocked and disappointed.

Dr. Karev has been notably missing from recent episodes of the medical drama. He is apparently visiting his mother but not answering calls from his wife Jo, or friend and "person" Meredith Grey.

Now it seems the reason for his absence will finally be divulged next week in what will mark the doctor's final episode.

It airs next Thursday on ABC at the show's regular shot of 9pm. Showrunners have confirmed that the hour-long episode will serve as the official goodbye to Karev.

Titled 'Leave a Light On', ABC confirmed it "provid[es] closure to his character’s exit".

Showrunner Krista Vernoff previously said: "We’re episode by episode, illuminating the story of where Alex is.

"It’s a bit of a mystery [what’s going on]... We don’t watch Jo in the same place that we watched her in last season. We did it as carefully as we could. But it takes a while to get there."

Chambers announced he was leaving the series after sixteen seasons last January.

He stated: "There’s no good time to say goodbye to a show and character that’s defined so much of my life for the past 15 years. For some time now, however, I have hoped to diversify my acting roles and career choices.

"And, as I turn 50 and am blessed with my remarkable, supportive wife and five wonderful children, now is that time. As I move on from Grey’s Anatomy, I want to thank the ABC family, Shonda Rhimes, original cast members Ellen Pompeo, Chandra Wilson and James Pickens, and the rest of the amazing cast and crew, both past and present, and, of course, the fans for an extraordinary ride."

ABC also released a trailer for the farewell episode. Prepare to get a bit nostalgic and teary.