The Series Finale "Black Rain", being Darker and Edgier taken Up to 11, has a lot of this, from Slender Man stalking Socrates, to Shadow electrocuting the water, to Socrates screaming as a person in a hoodie and a gas mask is sprinting towards him before the line goes dead.
Socrates: He's not really doing anything. He's just kinda staring at me. Wait, never mind. Now he's sprinting at me. Sprinting at me very fast... OH MY GOD! NO DON'T DO IT! AAAAAAUGH!
- Then there's the ending: Thunderstorm and Shadow are apparently killed by the Slender Man. And it's implied that he's supposed to be a good guy!
The lights flickered once more before they finally went out completely.
Everyone in the group suddenly hugged each other, deathly afraid of losing anyone.
And a moment later, they heard Thunderstorm's screams. He screamed and screamed as loud as he could, sounding as though his terror quadrupled as he continued to scream. The scream turned into a screech, and the screech turned into a shriek, and then the shriek continued for a solid three seconds.
It happened so suddenly, they were almost deafened by the silence.
Five seconds later, the lights came back on, and when it did, the door was open, allowing the sunlight and cold air of the mountain to flow through the room.
Everyone remained frozen on the spot for at least another minute, each of them too horrified by what had transpired to budge from their spot.
Dr Thunderstorm was gone.
- Fridge Horror: Dr. Thunderstorm says that the Slender Man came when he was a child, and "He took another last time." Meaning Dr. Thunderstorm was perfectly willing to let someone else suffer a terrible fate in order to save his own skin once and probably would've done it again.
- Shadow ripping Jack's circuits from his chest. Even though he has auto repair, it is still probably one of the most brutal injuries he's recieved in the entire series.
- The Mind Rape scene where Shadow "probes" Jack's mind, and Jack is described as being in pain during the whole ordeal.
- Adult Fear comes into play when the group learns that the guy who tried to kidnap Socrates in Part 2 had a knife the whole time.
- Especially when the already horrified Socrates points out that he might come back when Eliot and his parents are home.
- It's even Lampshaded:
Somehow, some psycho with a knife that they couldn't identify had become ten times scarier than any mad scientist or alien dictator that had tried to destroy them previously.
- The guy with the knife easily took out Shadow, the robot that posed a legitimate threat to the main cast, by stabbing him in the head and then pulled the knife out effortlessly to chase Dr. Thunderstorm. And if that wasn't enough, he then dodges the Servant Ray's beams without even trying.
- The scene on the ship at the beginning takes very obvious cues from slasher movies. Sure, nobody got killed, but it was still pretty dark.
Guy in Engineering: MOMMY! MOMMY! I DON'T WANNA DIE! WHAAAA!
- The tape the main cast finds, being based upon the ones from totheark and the Observer, is naturally this trope in motion:
There was brief moment of silence of nothing but blackness on the screen, and what seemed to be the distorted, distant sound of a song being played backwards, then a message appeared on the screen, still flickering and trembling slightly. All the 'o's had 'X's drawn through them.
Socrates' expression dropped.
The screen blacked out again and showed what appeared to be distorted, black and white footage of a country road. More words appeared on the screen.
The screen blacked out again and an eye appeared in the middle looking around in all directions.
The choppy music continued. Several more distorted, still black and white, images flashed across the screen that were for the most part unrecognizable, before finally coming to a picture of what seemed to be a forest.
A shot of a dripping facet appeared
Another shot of someone close up, licking their lips.
The shot didn't change, but the person's nose started bleeding.
Another shot appeared of Calvin and Hobbes playing Calvinball.
A shot of Brainstorm's silhouette appeared.
A pair of eyes opened in the silhouette, clearly not Brainstorm's, and looked all around.
Tentacles appeared from out from behind Brainstorm's back before cutting to another shot of a clock.
The video then began reversing through everything that had been shown, prior. More words appeared.
Suddenly, the screen cut out completely, and the music stopped.
There was a silence.
And with that the tape ended.