The newest addition is Michael James Shaw, who has been locked in to play Mercer.
Mercer had a heavy presence during the final arc of the comic books the series hails from.
In the comics, he plays the Commonwealth Army commander, a man who stands out thanks to his red armor and a pair of axes he uses as his weapons of choice.
If you watch The Walking Dead online, you know the Commonwealth arc is only just beginning, so it makes sense to reveal who will be playing such a pivotal character.
Shaw is well-known for his appearances on Bull, Blue Bloods, and Blood & Treasure on the small screen, but on the big screen, he has appeared as Corvus Glaive in Avengers Infinity War and Avengers Endgame.