1) Spherical creatures with bottomless throats and a voracious appetite, the eponymous entities of the first novella in the Stephen King quartet Four Past Midnight.
The world of life and consciousness is forever passing down the stream of time, and the uninhabited, chemically inert world left behind - inadvertently visited by sleeping passengers on a plane that flies through a time rift - awaits being carved up by the jaws of what one character refers to as the timekeepers of eternity, but which might more accurately be described as the blow-fly larvae of the space-time continuum. From a distance, the sound of their munching is somewhat like the sound of radio static ... and that is as close as you want to get. As another character, Craig Toomey, envisions them, these creatures are purpose personified; in the horror stories he heard as a child from his insanely pushy father he was told how their sole purpose is to chase down all the lazy people who are not working frantically enough and eat them alive.
2) Referred to when something urgently needs doing, like a college essay due in the morning.
But the sound-wave rolled on toward them - the crunching, smacking, eating sound of the langoliers. (Four Past Midnight, p. 233).
Gotta go. Thesis to finish by next week. Langoliers.