Scott Ian's Walker from Season 5
Scott Ian the rhythm guitarist for Anthrax is a huge The Walking Dead fan back when it was just a comic book. His dream of being a walker on the TV series was realized in episode 5.12, Remember. Scott is the walker hiding in the trash when Rick is looking for his hidden gun. Carl kills him with a pole.
Scott also appeared as a walker in the webisodes that is the Biker Girl Walker backstory. He appears in webisode 6.