The zombies in Grip of the Shadow Plague are living underground at the Lost Mesa preserve, each with its own headstone. When the zombies are hungry they ring a bell, and are fed a red, goop-like substance by Hal. After the magical object that Kendra and her team were supposed to get is found to be at Fablehaven, KendraWarren, Dougan, and Gavin leave. Then, the zombies escape a few nights later and help in the fall of the preserve. Zombies have nearly no intelligence, acting almost solely on instinct. If they have food, they will stay where there are, if they don't, they will go and seek it out. Nothing is left of the humans the once were. They can be sensed by a Shadow Charmer and controlled by Viviblixes.

Zombies are part of the class of Restless beings called Corporeal entities.