This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / The Langoliers
The Langoliers, questionable SFX aside, are just terrifying. They're Clock Roaches that devour the previous time continuum in order to extend eternity, but if that's all they are, they'd have had no reason to turn away from the rest of the main cast in favor of hounding down the fleeing Toomy, from whose childhood terrors come not only the name they bear throughout the story, but the manner in which they finally kill him.
That's bad enough to begin with, and it gets worse when you consider that Dinah, having been in and out of Toomy's head throughout the story, appears to him in the guise of an angel in order to lead him out of the terminal and away from the airplane, so that he'll bait the langoliers away from it for long enough to give everyone else a chance at escape. She was also present when he talked about the story his father'd told him, and how terrified he'd been of the man. Did the Clock Roaches take the shape of Toomy's terrors in order to torment and kill him? Or were they given it, by a dying little girl who quite coldly chose to murder Craig Toomy in hope of saving the other passengers' lives?
What about Nick and all the other people that vanished in the flight? Where are they now?
The (third-person omniscient) narrator says, in so many words, that "Nick Hopewell ceased to exist." Given that he left behind in so doing the same sort of impedimenta as did the other vanished passengers, the reader may safely surmise that the same thing happened to them.
Toomey's equally-insane, abusive father has a surprising amount, despite his limited role. The implication that he may have driven his alcoholic wife nuts certainly helps, but what really drives it home is the way that, despite being long dead when the story opens, he nevertheless has a role second only to the Negative Space Wedgie in driving the plot, entirely as a result of the effect he had on his son.