Considering this is an adaptation of a story by (the son of) one of the most acclaimed horror writers ever, this shouldn't be surprising.
Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. You Have Been Warned.
- The Grabber. A child abductor/serial killer with a penchant for creepy masks. He is scarier than the actual ghosts. We never quite learn why he kidnaps the boys, only that he likes to play a sadistic game called "naughty boys" where if they attempt to escape, he beats and kills them.
- The "naughty boy" game has a bizarre ritual quality to it that is itself pretty terrifying; the Grabber initially acts relatively polite and diffident (for a devil-masked serial killer, anyway) but goads his child victims into transgressing his "rules" and thereby giving him an excuse to vent his rage against them. The image of the Grabber awaiting his victim at the top of the basement stairs — fully masked, knees spread, stripped shirtless and holding a doubled-up belt — is ghastly. To say nothing of, well, the name. (the Grabber's promise to Finney to "never make you do anything that you won't like" is certainly sinisterly suggestive on this front) And the vicious beating is only the first part of what "naughty boy" apparently involves...
- The titular phone. While it actually is useful to Finney in allowing him to speak with past victims, we know very little about it. The only ones who ever hear it ringing are Finney and the Grabber, and the latter is actually afraid of it, not wanting to believe in it and insisting it doesn't work (justified, as his victims are able to use it). Also, at two separate points in the film, Finney can see the phone breathing.
- The title sequence alone is terrifying thanks to its shaky editing, constant jump-cuts, and especially the heart-pounding music
filled with what sounds a lot like screaming. - The first appearance of Griffin in the basement. He appears dangling in mid air in the darkness, suspended from nothing, with his throat gashed open, blood dripping on the floor.
- Vance Hopper, a violent bully who utterly terrified Finney in a store by brutally beating up someone who made him lose a pinball game. Honestly? He could have the main villain of another film. He’s probably the only ghost in the movie who’s legitimately frightening, as the other 4 ghosts are just innocent and genuinely kind victims.
- Gwen's spanking. Although her father feels she deserves a punishment, she bawls so loudly it's horrifying to imagine how much her bottom hurts.
- Finney's first quasi-successful escape attempt. On the ghosts' advice, he actually manages to get past the sleeping Grabber and out of the house, but the Grabber wakes and chases after him. Finney screams for help and several porch lights along the street turn on, indicating that some of the Grabber's neighbors have heard him and might come to his aid. Then, the Grabber tackles and pins him to the ground, holds a knife to his throat, and promises to "gut [him] like a pig" if he makes more noise. Finney keeps quiet and the porch lights go off as the neighbors presumably decide it was a prank or false alarm. It's a terrifying and heartbreaking sequence reminiscent of the scene in Halloween (1978) when Laurie knocks on doors begging for help only for people to dismiss it as a Halloween prank; and it emphasizes just how much Finney has to rely on himself (and the ghosts) to escape his situation. No (or at least very few) adults are coming to help him.
- The Grabber's mask has interchangeable lower portions allowing for changes in expression: a grin, a frown, or a complete blank with no mouth at all. This is reflected in his vacillating behavior as well — he flips from overt threats of violence to acting conciliatory or even tearful, sometimes in the course of the same sentence, making it unclear which parts of his demeanor are genuine and which are a performance and keeping his victims perpetually on the wrong foot.
- The Grabber's demeanor is terrifying at the best of times but there's something especially chilling about seeing his demeanor change when Finney confronts him about why he's lingering in the basement. He actually has tears in his eyes, but they certainly don't bring about a change in heart.Finney: If you weren’t gonna feed me, why’d you even come down here?The Grabber: Just to look at you. I just wanted to look at you. (Beat.) I'll go.
