The Zombie Horde is a large group of Zombies led by Vaurien Scapegrace. They were created by the Revengers' Club to attack The Midnight Hotel so Billy-Ray Sanguine could steal a Remnant with a Soul Catcher.
After Vaurien Scapegrace was killed and revived as a Zombie, he was given a task to recruit more Zombies to create an army. Scapegrace recruited Gerald, who he renamed Thrasher, and put him as his second in command. Scapegrace then recruited more Zombies, giving them names such as Slasher and Dicer, but then Zombie One, and so on. Scapegrace tells them that they must not eat any human.
Later at The Midnight Hotel, the Zombies all have a symbol carved on them so that they can enter the hotel. However, they eat a human and the Zombies go crazy. The Zombies go on a rampage and attack the Hotel. Skulduggery Pleasant, Valkyrie Cain, Billy-Ray Sanguine, Anton Shudder, Miss Nuncio and Mr. Jib all defend the hotel against the Horde. Miss Nuncio and Mr. Jib are both killed by the Zombies.
In the end, the Zombies are all defeated, and Scapegrace and Thrasher flee. But Sanguine still manages to get a Remnant.