In a conversation with Alex Cooper on the “Call Her Daddy” podcast, highlighted by Entertainment Weekly, Rhimes was asked which character’s death was the most painful. Rhimes singled out the demise of Dr. George O’Malley, portrayed by T.R. Knight. An original character from the show’s beginning, O’Malley’s tragic end occurs between the Season 5 finale and Season 6 premiere. Rhimes reflected on this, noting the challenge due to George’s popularity and Knight’s amiable nature.

George O’Malley starts as a novice surgical intern alongside Dr. Cristina Yang (Sandra Oh), Dr. Izzie Stevens (Katherine Heigl), Dr. Alex Karev (Justin Chambers), and Dr. Meredith Grey (Ellen Pompeo). Initially clumsy, earning the nickname “007” for nearly botching an appendectomy, George evolves into a skilled, compassionate doctor. His character arc takes a pivotal turn in Season 5 after a trauma rotation with Army vet Dr. Owen Hunt (Kevin McKidd), leading George to enlist as an Army medic. However, a twist of fate disrupts any intervention planned by his peers.

As George’s friends, including their unofficial mentor Dr. Miranda Bailey (Chandra Wilson), search for him, thinking he’s with the chief, Dr. Richard Webber (James Pickens Jr.), George has already left the hospital. Heroically, he saves a girl, Amanda (Shannon Lucio), from an oncoming bus but suffers catastrophic injuries as a result.

While George’s fellow surgical residents and their former chief resident and defacto den mother Dr. Miranda Bailey (Chandra Wilson) try to find George, believing he’s in the operating room with the chief of surgery Dr. Richard Webber (James Pickens Jr.), he actually left the hospital shortly after handing in his resignation to Richard. On the way to see his mother, George saves a girl named Amanda (Shannon Lucio) from the path of an oncoming bus but ends up dragged by the fast-moving bus instead, removing several layers of skin and leaving him with ultimately fatal injuries.

As Meredith and her friends race to save a man whom they only know as “John Doe,” George, unrecognizable, “writes” on Meredith’s palm with his finger and eventually gets her to understand his message: “007.” Realizing that John Doe is George, Meredith and the rest of the Seattle Grace crew watch in horror as George dies from his injuries on the operating table. As Shonda Rhimes told Alex Cooper, T.R. Knight, incredibly insisted on playing George after the injuries that made him into a total stranger.

“T.R. was so amazing because he didn’t need to lay on that table,” Rhimes said. “But he was like, ‘I’m gonna do the role, even though you’re never gonna see my face’ […] He was wonderful. I mean, it broke me, so I knew that the audience would respond to it, but I really loved it.”

Not only that, but Rhimes says she’s pretty sure nobody on set knew that was Knight. “Nobody knew who George was. Nobody,” she recalled. “I’m not even sure all the cast knew. Because, technically, his character had left to become a soldier, so he was already gone. I know that certain members of the crew knew, and T.R. was determined that he would be the body lying on the operating table. He would be the body that you saw every single time, which is why you got to see his beautiful blue eyes.”

Unfortunately for both Dr. George O’Malley and T.R. Knight, Season 5 of “Grey’s Anatomy” was the perfect time for George to exit, because he had absolutely nothing to do narratively for the entirety of said season. After four seasons of legitimate character growth — including the loss of his beloved father and a hasty, ill-advised marriage to Sara Ramirez’s orthopedic surgeon Dr. Calliope “Callie” Torres — George is basically a background actor in Season 5, stuck reacting to events that happen to other characters rather than experiencing anything directly by himself. A perfect example is the Izzie storyline that takes up the back half of Season 5, where Izzie realizes that she has stage IV cancer that’s spread throughout her body; as Izzie’s best friend and her ex-boyfriend, George should be there for Izzie. Instead, he’s literally the last person to even find out that she’s sick, and he gets one line to react to that.

George is a wonderful character and Knight is a genuinely phenomenal actor, but all good things must come to an end, and George’s time on “Grey’s Anatomy” came to a natural — if brutal — conclusion during Season 5 of “Grey’s Anatomy.” If you want to experience his entire journey, the series is available to stream on Hulu and Netflix now.