Actor T. R. Knight made a surprise appearance on the December 3episode of "Grey's Anatomy" and took to his Instagram page afterward to pay homage to his co-stars.

T. R. Knight is famous for starring as Dr. George O'Malley on 'Grey's Anatomy," a role he held from 2005 to 2009, the first five seasons of the medical drama.

Knight starred alongside Ellen Pompeo, who plays Dr. Meredith Grey, James Pickens Jr. (Dr. Richard Webber), and Chandra Wilson, who stars as Dr. Miranda Bailey, as one of the five original interns in the series.

It's been 11 years since "Grey's Anatomy" fans last saw Dr. George O'Malley on the series, but he made a surprise appearance on Thursday night's episode when he appeared in one of Dr. Grey's dreams on the beach.

Following his character's surprise appearance, Knight shared a photo on Instagram of himself, Pickens Jr., Pompeo, and Wilson, at the beachside, along with a note that read:

"George O'Malley will always claim my heart. Thank you to Ellen, Chandra, Jim, Krista, and all the familiar faces for once again sharing your beautiful light."

Ellen Pompeo attends the GLSEN Respect Awards on October 19, 2018 | Photo: Getty Images

Knight captioned the post with a red heart emoji. In another post, the actor

tribute to Pompeo. He shared a picture of them sitting on the beach sands with their backs against a rock.

In the post's caption, Knight described Pompeo as the type of actor he is always grateful to act with and an embodiment of truth. He added that their characters O'Malley and Grey love each other.

Knight also enjoyed the scene and said he loved Grey's vision of O'Malley because she saw his humor, kindness, generosity...

However, Knight said O'Malley's love for Grey could not hold a candle to the love he has for Pompeo. Pompeo replied to Knight's post in the comment section, saying she is lucky to have a friend like him.

O'Malley's surprise return to "Grey's Anatomy" is not the first an old character of the series will be making in its new 17th season.

The season premiere ended with Dr. Grey's late husband, portrayed by Patrick Dempsey, returning to her in her dreams.

Speaking on how the recent episode came to be, the series' executive producer Krista Vernoff said she thought about the concept while walking on the beach and pictured Grey walking on the beach with O'Malley.

Vernoff felt joy at the thought and told Pompeo about the idea. The latter also loved it and suggested that Dempsey should also be brought back.

Knight also enjoyed the scene and said he loved Grey's vision of O'Malley because she saw his humor, kindness, generosity, and all his good sides, which was a great way to remember him.

Following Dr. Shepherd's surprising appearance in the season premiere, executive producers Andy Reaser and Meg Marinis told PEOPLE that wonderful and completely surprising things are possible on the show.

With O'Malley's appearance, fans would be left wondering what other possibilities the producers have in store for them in what has been an amazing, soul-lifting ride in "Grey's Anatomy's" 17th season thus far.

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