T.R. Knight talks George's surprising 'Grey's Anatomy' return, reuniting with Ellen Pompeo

The nostalgia continued on "Grey's Anatomy" this week, as the show welcomed back another former star in one of Meredith Grey's COVID-fueled dreams.

T.R. Knight, the actor who played George O'Malley on the first five seasons of "Grey's Anatomy," returned at the end of the Dec. 3 episode for an emotional reunion with not just Ellen Pompeo's character, but with Miranda Bailey (Chandra Wilson) and Richard Webber (James Pickens Jr.), too.

As fans will recall, George, who had been a series regular since the series premiere, died in the season 5 finale, which aired on May 14, 2009, when he pushed a pedestrian out of the way of an oncoming bus, thereby saving their life. He was brought in as a John Doe and it was Meredith who realized it was George when he signed "007," the character's nickname, in her hand.

"Ellen is the kind of actor I’m endlessly grateful to act with," Knight wrote on Instagram after the episode aired. "She’s the embodiment of truth. George and Meredith love each other, for sure, but I don’t think he can hold a candle to love I have for Ellen."

Pompeo replied to her former co-star in the comments, writing, "I’m so lucky to have a friend like you."

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Knight said in an interview with Deadline he thought George "already" had closure on the show, but his husband, Patrick Leahy, convinced him that "sometimes closure's shutting a door, and sometimes it's revisiting a familiar room, and finding what brought you joy."

Krista Vernoff, showrunner for "Grey's Anatomy," told the outlet she felt "this was a beautiful bow" on George's story, but to "never say never" on the matter of whether he could show up again.

As for Knight, he said this was "the ending I never expected and couldn't possibly have expected, in so many ways."

This marks the second "Grey's Anatomy" alum to return to the show in season 17, following Patrick Dempsey's McDreamy-like homecoming as Derek Shepherd in the Nov. 12 season premiere.

"Grey's Anatomy" airs Thursday nights at 9 p.m. ET on ABC.