"To a certain extent, all of them. But Negan's not dead, he's still out there," Kirkman told ComicBook.com at San Diego Comic-Con when asked which character he'll miss writing the most.
"Writing that last issue, there was definitely — I won't spoil things specifically — but there's things in the back of my mind where I'm like, 'Oh, I wonder what Carl does next, I wonder what's going on.' But it's not right to continue the story from that point because that's the definitive end. But I'm gonna miss all those characters."
But for Kirkman, who surprise ended the book earlier this month after a near 16-year run, "It's still very raw for me because it's all so new," he said.
"But yeah, it hasn't been that many months that I haven't been writing issues, so it's still kinda sinking in."
Because the reformed Negan didn't reappear since finding peace with himself in December 2017's issue #174 — currently his last appearance aside from a "cameo" in #193, the book's final issue — fans are hopeful a spinoff or continuation could emerge.
When asked about Negan during his In Conversation with Robert Kirkman panel at Comic-Con Thursday, Kirkman said the return of Negan was "an option."
"I think that's a really cool tidbit. Theoretically living in that farmhouse. Theoretically there might be a story to be told there; it's possible that's my escape hatch if my career ever takes a hard nosedive, just roll out a Negan comic," Kirkman said.
"There's no plans as of yet, but there's an option there, sure."
This comes after Kirkman was sure to confirm Negan's fate in the multi-page goodbye letter penned as a "thank you" to readers: in it, Kirkman signed off by writing, "P.S. Negan Lives."