When I placed my last order with Mantic Games for the Here's Negan board-game, I also ordered a set of The Walking Dead Corpses. This set comprises of six figures - 4 zombie corpses, 1 human corpse and a dying human. All are sculpted on 25mm diameter bases and are made of resin. The detail on them is very good.
This is not an essential purchase as they serve no purpose in the game. However, for me, in any zombie apocalypse game, corpses are an essential part of the scenery. Like zombies, you can never have too many corpses, in my opinion. This set costs £14.99 from the Mantic Games webstore, so they're not cheap by any means. Although sold as a The Walking Dead accessory set, they could be used in any zombie apocalypse game.