- There is one scene where Lina and Gourry fight trolls. Swept away by magic in the anime. The novel goes into extreme detail about their bloody reminants, painted all over the inn's walls.
- Copy Rezo in the novels...he gains some extra mouths on his body to multiply the number of spells he can use at once. Anime? They're on his hands. Novels? They're his eyes. Physically. That's why they're closed.
- Shabranigdo being reborn in the first book. Rezo's flesh melts away, and Shabranigdo himself looks creepy as hell.
- Ragnut Rushavna. A spell that turns the victim into a giant hunk of fleshy meat that gets eaten over and over again by snakes. It won't stop until the one who cast the spell is detained, quintessentially making the victim immortal. Never appeared outside the novels for a reason... It's used on a bumbling sorcerer in one of the novels, while the fellow sorcerer who's rivaling him is beheaded. In the anime, they're merely turned to stone.
- The novel The Silver Beast follows the story of a cult worshiping Shabranigdo, and most of its members are rather gruesome-looking chimeras. One of them is a skinny beast-like creature with a brain on its back, and both are their own person. A far cry from Zelgadiss...
- Surprisingly for many people used to the anime's slapstick tone and tendency towards Disney Deaths for minor characters, there's a certain amount of this, often in the form of Body Horror, in the novels. (Two words: Raugnut Rushavna. If that doesn't make you shudder, you haven't read the second novel. Also notably, what happened to Copy Rezo in the third book is almost enough to make you feel genuinely sorry for him.)
- Then there's the part in the anime where everyone is surprised to see Syragg rebuilt after it's destruction and all of the people who were killed walking around normally. When Sylphiel sees her father again, he puts her hand on his chest and she notices that he has no heartbeat. He then tells her that Syragg is a literal ghost town with shadows of the fallen citizens who are controlled by Hellmaster Phibrizzo and that their bodies are trapped in a sleep like state in the underworld. Things get considerably worse after that when all of the ghosts attack the main characters, as they make their way to Phibrizzo's lair.
- Also, what happens to Hellmaster leading up to his death is pretty disturbing looking (and sounding, with the screaming he does during it). Though he DID have it coming.
- Another great example is when Hellmaster rips out Amelia's soul in front of the rest of the team toward the end of NEXT. The voicework in particular sells it in both languages, with Amelia in unspeakable pain for a few moments before... stopping in Zelgadis' arms, and then Zelgadis absolutely losing it. And not only that, but when this aired Amelia's Contractual Immortality wasn't guaranteed, so for people watching at the time? Hand-over-mouth horror.
- Watching Eris slowly fall and twitch on the ground while lying in a pile of her own blood and then get vaporized was a giant wake-up call to the audience that the show had stopped kidding around. May count as a Cerebus Syndrome moment for the show; in the original books, her death was much less gruesome. Oh, and then an episode later, LINA has the same thing happen to her, making it very convincing that she might not survive this one....
- In an early episode of the first season, Zelgadis manages a moment of this when he ambushes Lina (who is unable to use her magic because it's "that time of the month") and Gourry with his two henchmen Dilgear and Rodimus. It ends with Lina facing Zelgadis alone, who immobilizes her by catching her shadow and then proceeds to use a spell that effectively electrocutes her into unconsciousness. The fact that Lina actually screams in pain as he does this doesn't really help.
Nightmare Fuel / Slayers
Nightmare Fuel is more prominent in the Light Novel continuity than in the anime; read the first book for example, then compare it to the anime. That said, they both have their moments. Spoilers below.