In the comic books, Glenn dies at the hands of a yet-to-be-introduced villain by the name of Negan. Rumor has it Negan may appear at some point in the sixth season. Glenn's death is arguably one of the most iconic and brutal moments in the entire comic book series. Seeing as Negan might be showing up soon, and the death is such a standout moment, it makes sense that the creators would want to play this one by the book.
In the scene in question, Negan and his group — called The Saviors — ambush Rick and the gang in the dead of the night. Negan selects Glenn for execution and bludgeons him with a barbed-wire-wrapped baseball bat. He beats him until he's unrecognizable.
We know, we know, there have been plenty of instances in which the TV series has strayed from the events in the books. We just figured this is one sequence the series might not want to skip.
