This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Dark Harvest
Log Entry #7 - Alex comes home to find his electricity cut off, his bedroom covered in Operator drawings, and when he goes into the next room, he sees a human hand reach out from the closet door and close the door.
Log Entry #12 - At first, everything seems totally fine with the Dark Harvest guys just hanging out with their friend. Until they decide to leave, finding one of the masked men standing on a driveway and when they try to approach him, he pulls a knife out and begins chasing them back to Greg's house. Then after they lock all the doors, they hide in the basement, only to hear footsteps walking around upstairs.
Log Entry #19-We haven't seen Slendy this confrontational in a long while. Then, as he leans out from behind the doorway at the very end... strange, ragged breathing can be heard.
Greg's gouged out, mutilated dead body, and the rest of Log 14-1 & 2
The unresolved conspiracies pilot video has an image from the results of the princeton experiments (starts at 1:49 Also it gets better when you realize that its just the results of ONE experiment and that they probably tried the same thing (albiet with minor modifications made to the procedure) with other people!
February 24th. Mother of God, February 24. Chris running upstairs to find himself faced with one of the masked men, only to run downstaris and out the front door to be faced with a whole group of them.
Log Entry #25: The Dark Harvest guys meet with Tribe Twelve's Noah. It starts off relatively normal (well, normal for the series), they come up with a plan to have Noah infiltrate the cult so they could all get some answers. Then Noah comes back, being chased by the masked cultists, and says that Slendy showed up before he booked it. And that's when the car decides to stall, followed by a cultist ending up right in front of the car. The lights go out, then flick back on just in time for a cultist's dead body to be thrown on the hood of the car. Then the lights go out again, and when they flicker back on yet again, guess who's standing in front of the car?
YMMV on the body hitting the car. The guys' screams are kinda Narmy.
Log Entry #26: After the events of the last video, the boys decide to try and get info out of Jesse. Unfortunately for them, Jesse takes this opportunity to lead them straight to his fellow cultists for their execution! The two almost get their heads chopped off, but manage to survive thanks to Jeff pulling off aBig Damn Heroes moment.
Greg's Final Log, the Slender Man shows up in Greg's house after he tells Jesse he wants to leave the cult. Then Jesse locks him in the basement for the Slender Man to come get at his leisure. Then there's that long, distorted shot of Slender Man looming directly over Greg, accompanied by creepy rumbling sounds that sound almost like vocalizations.
It's also one of only a few times in the entirety of The Slender Man Mythos that we see Slender Man walking around as opposed to just kind of standing there menacingly.
Log Entry #28: After months of inactivity, the boys find out that Jesse was found decapitated on a farm. A few days later they receive a tape showing the Order executing Jesse, with a warning: while the Order is personally forbidden from killing the boys (because it has been foretold that Slender Man will kill them), if either of them attempts to contact the Order again they will find and kill everyone they love, and continue to torture them for years on end until Slendy finally comes for them.
Log Entry #29: Chris and Alex meet up with a very frightened Heather McComber, who reveals that she is an unwilling member of the Order, forced to join as a teenager. She informs them that the cult now has chapters worldwide, and is preparing to initiate "the Harvest": an attempt to open a rift to Slender Man's realm by murdering as many people as possible and collecting their Life Energy. Oh — and the boys' YouTube channel is directly responsible for the surge in cult members, as their videos have not only "proved" the existence of the Slender Man, but encouraged fellow victims to turn to the Order for answers.
As Chris leaves the train station, he passes a man in a black hoody; in the video's final frame, he states that the man was probably a member of the Order, adding that "a lot has changed [since the video was filmed] and a lot is going to change. These videos are all we have left..." Given the Order's previous threats, this doesn't bode well at all.
Log Entry #30. The Order makes good on the first part of their threat: several days after the previous video, Chris gets a call from Alex, who informs him that he found his parents and sister shot dead in their basement. Chris returns home and frantically searches his house — and finds his father's bloodied body strung up in the shower.
We're also told that Chris's mother was murdered, but we never see (or hear) what happened to her. The jump cut after Chris finds his father's body suggests that some of the more graphic footage might have been removed; whatever happened to Chris's Mom, it wasn't very pretty.
Correction: Chris didn't see his mother's body. Several days later, however, the police found her beside a freeway, dead of multiple stab wounds. Not very pretty, indeed.