Langoliers

The Langoliers are the titular villains of the Stephen King story The Langoliers as well as the television mini-series of the same name, they are sphere-shaped monsters with immense appetites and the ability to travel through time: they are described as timekeepers of sorts who devour those who are displaced in time, destroying remanents of the past as a kind of temporal scavenger/predator.

Although mentioned throughout the story, with their presence being felt by some psychic characters, the actual Langoliers did not appear physically until near the end of the tale - as is often the case with supernatural beings in psychological horror.