No matter how hard they try to play it for laughs, they couldn't cut down on the nightmare fuel that is the Nazgūl.
Venom's level in Marvel Super Heroes. It's loaded with Spider-Man: Web of Shadows levels of symbiote goo which you can get caught in, the enemies are half-possessed symbiote victims, and then there's Venom himself. Special mention goes to Venom's rather unexpected Jump Scare.
Venom can also become a Big Fig (similar to Hulk and Abomination). Only problem is he literally TEARS HIMSELF IN HALF to do so! With the looks, and the screeches of pain, it looks very horrifying. Considering that he shows a host inside him during his battle, the transformation must be excruciating.
Lizard's grab involves him eating his opponent.
Ant-Man's special has him shrink himself further than in normal gameplay, enter his opponent's body, and explode them from within.
The final boss of LEGO Marvel Superheroes is a brainwashed Galactus. Loki plans to make him devour Earth and Asgard.
The Scarecrow fight in the fourth level of Batman 2. He uses fear gas to make Batman and Robin hallucinate that he's giant, and by the point that he throws all three fear gas bombs, the screen gains a wavy effect like you were viewing it underwater and tinged yellow-green. A brilliant choice of suit makes it so that fighting the Mooks as Batman makes them appear as skeletons due to the Sensor Suit's X-ray vision when next to a character, all while seeing a towering Scarecrow laughing in the background.
Arachnophobes won't like the Spider Bomb weapon in LEGO The Hobbit. It's a spider's egg sac that explodes into a swarm of spiders when thrown. If an NPC is in the area, they will swarm around them and damage them. Several bombs can be thrown to create a large mass of them, but they eventually fade.
Black Hand is in LEGO Batman 3, with a surprisingly horrifying character model. Mercifully, he's not in the main game.
While they rather mercifully cannot hurt you, the Weeping Angels are shown to exist in the LEGO Batman universe.
The statue of Abin Sur during the Indigo Tribe level in LEGO Batman 3 might not make any sense at first, but comics fans will know that this is because Indigo-1 murdered his daughter. This means that when Flash, Cyborg and Martian Manhunter step foot on the planet, they're fighting a child-murdering sociopath at the head of an equally sociopathic group of criminals.