He's likely referring to the character T-Dog, who was a member of the main group from season one until he was killed off during Killer Within", the fourth episode of The Walking Deads third season. T-Dog was the center of criticism thanks to his being just a random black guy who--on a series praised out of the gates for some of the best TV character development / performances in this century--was seemingly tokenized wallpaper, his lone moment of note coming early in season one where he was largely a victim to the Merle Dixon character. Ironically enough, one of the series' most celebrated characters was a black woman--Michonne--was introduced in the same season the weak T-Dog was killed off. This generated new criticism that one of The Walking Dead's MVP characters only worked that way as she was a creation from the comic books, yet when the showrunners/writers were free to create their own black character, the result was marginalized T-Dog--again, he was one of the core group characters from the beginning, yet every other surviving character had strong development and focus.
There's more, but for now, look no further than the Star Wars sequel trilogy, where Disney/LFL--in bringing the franchise back to the big screen, Kennedy, J..J., et al., had every opportunity to create a new, strong black character for a new generation, yet Disney/LFL had an agenda: use the one Black male lead (Finn as portrayed by John Boyega) and define him as a tokenized embarrassment by making him a long-lived Hollywood stereotype of Black men: a comedic sanitation worker (of all things he could have been, which rendered the idea of his being a trooper into a meaningless visual), then, he had to be named by Poe (historically dehumanizing to Black people, particularly to descendants in the slave/colonial nations), and he largely screamed and panted throughout TFA. Message from Kennedy, J.J., et al. well received. That was no accident or misunderstanding. Add John Boyega's GQ interview where he laid out the mistreatment to himself as an actor and the racially offensive marketing (marginalizing) of his character, and yet again, deep into the 21st century, you have racialized token characters from the media corporations who cannot stop selling their "progressive" status.