"Sometimes people pitch to me, 'Dude, wouldn't it be so cool if you did a Glenn origin movie?'" Yeun told IndieWire. "And I'm like, 'No, that'd be horrible.' That was so long ago. I was another person. I don't think I could go back there. That person was inherently trapped in whatever people thought he was. I fed into it and I believed in it, too — until I got out."
Glenn was killed off in the Season Seven premiere, murdered by a baseball bat-wielding Negan (Jeffrey Dean Morgan), but the series infrequently brings dead characters back by way of flashback or hallucinations.
Such a return isn't likely for Yeun, who has moved past his time as the pizza boy-turned-apocalypse survival expert.
"I left Walking Dead and I kind of had an existential crisis — not because I longed to be back there, but because I was made to feel the loneliness of life, which is that decisions aren't made for you," he said.
"You get swallowed up by whatever the thing that you're a part of. You get out of that show, and you're about to have a kid, and you're an adult now. And you go, 'Holy sh-t, I am in charge of my life. I am making choices. There's no next step."
Glenn's death-isode was followed by a cemetery-set installment of live aftershow Talking Dead, an experience Yeun recounted as "bizarre."
"It never rains in L.A., but it was raining that day, and they only had black umbrellas," he said. "We were in a f—ing mausoleum. Everyone's in dark clothing. I was like, 'This is so bizarre, it's like a funeral.' It was perfect, because it was like, this dude is dead. It reached out of the screen and became an experience for me."
Yeun has long accepted and embraced Glenn's brutal and gory death, calling his ext from the series "a natural end."
"Everyone felt it. I wasn't pining to be off the show. It was just the story, and you service the story," Yeun said. "Also, there's something very beautiful about the end, turning the page and closing the book."
He openly admits he no longer watches the series — he's kept busy with roles in Voltron, Okja and 2018 festival favorites Sorry to Bother You and Burning — but is still tight with his old castmates.
"I don't watch it as much," he said. "I'm still really close with all the co-stars, so I get the down-low on what's going on."
Yeun previously penned a tribute letter to Rick Grimes actor Andrew Lincoln, who exits the series this upcoming half-season. In the letter, Yeun said he "learned quite a bit" during his seven years starring alongside Lincoln, who he called an "incredible leader" and "one of the greatest."
AMC has since launched ambitious plans to develop future Walking Dead television shows and movies, any of which could turn an eye towards exploring fan-favorite characters — living or dead.
The Walking Dead Season Nine debuts Sunday, October 7 at 9/8c on AMC.