*cracks knuckles*
Dead Birds: The scene where the gal is in the room alone and there's a kid running around. He hides under the bed and she brings her lantern and crouches down to try to see him but she can't. ...So she gets down lower, the lantern light flowing over him a bit more and he suddenly faces her and it's the hideous monster face that repeats a lot in that movie.
The Babadook: When the mother is lying in bed and the creature starts scuttling on the ceiling above her and climbs into her mouth.
Case 39: When Zellweger goes to pick the little girl up from group and already kind of suspects what she is and what she's done...she sees her through the classroom window, whispering to another little girl. Briefly, the evil child's face deforms in a very subtle way as she transfers this dark secret to the other child.
The Last Will and Testament of Rosalind Leigh: The entire thing is a buildup of tension and you gotta let it work on you. Because when you get to the part where he has the nightmare about the creature, this thing slowly, subtly emerging from the shadows of the hallway and suddenly its hand jerks out to point at the saying on the wall. I jumped!
Lovely Molly: The scene where she's got her video camera and she hears that someone calling her name and coming up the stairs. We see nothing but hear her voice and she's freaking terrified as she stumbles back into the bedroom and closes the door, the locks being manipulated and forcing her to run into the bathroom. She's breathing heavy as she sits on the floor or sets the camera down, I can't remember which, but there's a clicking sound...like hooves...and the sound of a horse breathing and still this purring voice calling her name. She's panicking out of sight of the camera as the locks on the bathroom door are manipulated, her voice begging this "thing" to stop and "not again" and the door swings open...and there's nothing there, nothing heard but the thing breathing like a horse, her voice suddenly cut off and completely silent.