- The Nullhullers (as seen in the picture) are a group of evil, blobfish-like trolls that can literally vomit all of their internal organs (sans the hearts) to make themselves more nimble. Should you try digging through the dung-scented contents of the organs for their gallbladders (the weak-point) all of the various organs and arteries will come to life to try and stop you! Body Horror at its finest.
- Changelings — they were Trolls taken at birth and experimented on to be able to take the forms of humans. And speaking of the humans they impersonate, they are frighteningly good at doing so and there's only one way to tell if someone's a changeling (their eyes).
- The story sets off with Kanjigar willingly stepping out into the light and turning to stone so Bular won't get the Amulet of Merlin. He committed suicide.
Becoming: Part 2
- Bular was inches away from catching Toby.
Wherefore Art Thou, Trollhunter
- Draal's brutal beatdown on Jim. Had he not been wearing his armor, Jim could've died right then and there.
- Bular standing as still as a statue outside of Jim's house, glaring at the Trollhunter within.Bular: Why isn't his head in my hands?
Gnome Your Enemy
- The Gnome (late known as Chompsky) has razor sharp teeth.
- When a security guard has the bad luck to happen upon Strickler and Bular in the museum, the former calmly tells the latter "I brought you a midnight snack." As Bular sets off after his luckless prey, Strickler smugly contemplates the apple he's holding — and we cut to black as he savagely takes a large bite out of it.
- Just how easy it is for Goblins to be killed. While the first Goblin was killed by a truck, the second was accidentally killed by Ms. Nomura simply by falling on him.
- Ms. Nomura. She's really a sadistic snake-like changeling who wield two scythe-like swords and whistles a disturbing tune (In The Hall of the Mountain King, to be exact).
- The Goblins' reactions to anyone who kills their brethren. They will devour the said offender, even if it was a complete accident.
- The very fact that Goblins can literally smell fear.
Win, Lose, Or Draal
- Ms. Nomura making her reappearance in Jim's home. She drugs Barbara to make her fall asleep and begins her attack on the armorless Jim.
To Catch A Changeling
- After thinking his dentist was a changeling, Toby notices that he's feeling numb. Then, the dental hygienist reveals she knows what gagglestack...and then shows her changeling eyes to Toby. And had not Blinky and Aaarrrgghh not arrived on time, she would've tortured information out of him regarding Jim.
- While playing a violent video game with Toby, Aaarrrgghh flashes back to his time as a Gumm-gumm. Even before we find out what's behind this, seeing the normally pacifist Aaarrrgghh with Black Eyes of Evil and bellowing with rage is incredibly unnerving.
Adventures in Troll Sitting
- The scene has a Goblin cooly and swiftly kidnapping Claire's baby brother. And the ending only heightens how disturbing the act was since, there are hundreds of other babies present.
- An In-Universe example — but when Jim is about to fight NotEnrique, the changeling stops Jim from doing so because then the Nunez family would react quite strongly to their child being gone.
- The Stalking — it's a flying Troll that is immune to sunlight and is a relentless predator that will stalk it's prey until death.
- Jim electrocutes himself in order to kill the Stalkling. It works, but if Aaarrrgghh hadn't made it in time to save him...
- The ending has two changelings interacting at the airport. Happy that the bridge to bring their leader over is near completion...
- Jim with Grit Shaka may be funny at first, until one realizes that the amulet makes him completely reckless that it convinces him to fight his most dangerous enemy.
Recipe for Disaster
- Strickler's true Troll form.
Claire And Present Danger
- Ms. Nomura's entrance. Jim has just finished a fight with a goblin horde. While he put up enough of a show to seriously impress Claire, he was without his amulet for half the fight. He's tired, in pain, and with visible scratch-marks, but trying to play it cool for Claire. Then... something in the dark begins to whistle 'Hall of the Mountain King'.Claire: Jim?Jim: (Visibly pales and readies his sword.) Run.
- Jim going in and out of consciousness after his fight with Ms. Nomura.
It's About Time
- At the end of the episode, Strickler has left the dentist, gotten into his car - and then realises the ring he used to control Angor Rot is gone. He looks in the car mirror just in time to see Angor Rot charging towards him.
Hiss Bang Bang
- At the beginning of the episode, a cute fluffy cat is scavenging for food around a cinema. It hears a noise coming from a dumpster, and when it investigates it finds three goblins. Who proceed to seize and devour it.
The Reckless Club
- Draal goes investigating the site of the bridge for signs of Gunmar. He hears a woman's scream and follows it to find a purse lying on the ground and an empty damaged car wedged in the branches of a tree. Shortly afterwards, Gunmar appears, wiping his mouth. The last scene he was seen in, Gunmar was complaining that the only thing he had been given to eat were cats. It's not hard to put the pieces together.
- The inevitable conclusion of the It's a Wonderful Plot nature of the episode: Without Jim's actions as the Trollhunter, Trollmarket never catches on to the Janus Order's schemes. When Jim realizes this at the last moment, all his attempts to warn his friends fail, as Toby doesn't believe him, and the trolls don't trust him, with Blinky even believing that Jim might be a changeling. On a desperate whim he's able to convince Strickler to trust him... just as Gunmar's invasion begins, heralded by a massive explosion outside. Jim's attempts to warn Toby and and his mom during the attack end with their phone conversations getting cut off, implying the worst for them.
- That last part bears some elaborating. Gunmar's invasion almost plays out like a PG-Rated version of Millennium's invasion of London. Half the city is on fire, people are being chased and cornered by Gumm-Gumm soldiers and their various war beasts, although we're conveniently spared seeing their exact fates. Goblins troll around in a stolen police cruiser, and Jim's mother is clearly hiding as Gumm-Gumms sack the hospital outside her hiding place. Knowing Gumm-Gumm eating habits it's safe to say what many of these people's fates are. To say nothing of seeing Steve getting carried off by a flying troll after being cornered on a statue.
In the Hall of the Gumm-Gumm King
- When the Trollhunters enter the Janus Order's base, the place is completely trashed leaving only human skeletons. We know that Gunmar despises changling and that Gumm-Gumms eat humans. Its pretty obvious what happened to them.
- Claire using enough of the staff's power to evacuate all of Trollmarket causes her to be psychically linked to Morgana and forced to help her. The final shot of the season is a terrified Claire springing out of bed after the bond is made in her dream.
- The ending, where Morgana creepily whispers that she will return before reaching out of the phonograph.
- Watching the teachers become more troll-like as a result of ingesting Gravesand. Miss Janeth in particular is unnerving with her body flinching in unnatural ways as she pounces on Eli.
So I'm Dating a Sorceress
- The video footage from the nanny cam of Claire rising from her bed, unconscious, under Morgana's control. One shot in particular where her head was lolling to the side with blank eyes as she conjures a portal
- Morgana's possession of Claire in the restroom. Claire washes her face up, and her reflection freezes and the room becomes dark. The reflection starts to talk to her in a creepily way, freaking out. When Claire tries to run out of the restroom she is pulled back and locked in while the reflection is turned into Morgana and leaves it before fully taking control of her body through her mouth.
The Exorcism of Claire Nunez
- This particular episode is one big horror movie. Special mention going to Morgana attempting to seduce Strickler to do her bidding by MORPHING Claire's physical body in Barbara's. And she almost succeeds.
A House Divided
- The scene where Jim carries out Merlin's plan to become a half-troll has an unsettling visual resemblance to a bathtub suicide - the inky fluid spreading throughout the tub looks like blood; Jim's life flashes before his eyes, as he builds up his resolve; and all of his friends (not to mention his mother) are right outside, pounding on the door, trying to tell him not to do it and to open the door. When they finally burst through the door, he's already submerged.