Hollowgast

Hollowgasts, or hollows, are a 'species' of creatures that was spawned from the infamous Experiment of 1908. Formerly peculiars led by Jack 'Caul' Bentham, hollowgasts are terrifying creatures who seek to consume peculiars, but will still eat anything in their path. Being invisible to most humans and peculiars, voracious and without humanity, they serve as the antagonists in the Miss Peregrine's Home for Peculiar Children trilogy.