The human-to-Zoanoid transformations, which are always Body Horror.
Sho fighting a doppelganger created from his own arm after his first death. (This was unfortunately cut out of the anime for timing purposes.)
Although they did pay attention to it. When Enzyme rips out Sho's Control Medal, the form he devolves into was obviously based on the monster that grew from his arm in the manga.
The first activation of a Guyver unit is always a horrifying experience.
And in the OVA movie, with the female Guyver, it is.
Sho's father turning into a Guyver-killing Zoanoid while being carried on his back. Combined with a Tear Jerker. It's one of the few times that the Narm of Enzyme's design is averted.
Aptom when he takes over someone's body. shiver
The most frightening example is when he absorbed Elegen, who cried out in terror before Aptom crushed his head, which was still attached to Aptom's body. The 2005 Anime made this scene even more terrifying, as Aptom stretched his arms out from where he was hiding, ensnared Elegen, and dragged him into the dark woods. Elegen's screams can be heard by the surviving members of Hyper Zoanoid Team Five as Aptom assimilated him into his body. Despite the fact that they're evil, it's hard not to feel scared for them.
Each time a Guyver is eaten, manga, OVAs, film or the anime it varies from this or extremely gruesome.
In a more down to earth sense of terror any scene where casualties occur at school. Such as a sniper killing several people in the first animated movie, or Team Five attacking the school in the first OVA.
The process of becoming a Zoanoid. While it does give humans enhancements such as a robust healthier body, it turns you into a grotesque monster.
Worse yet, it also deprives the subject of their free will, making them a mindless puppet for a Zoalord to control. Once the subject's mind has been taken over, they do heinous things to innocent people or even the ones they love; such is the fate of Sho's father and the men of Takeshiro Village.
Failed Zoanoids or those who never completed their transformation process suffer the fate of their bodies gradually breaking down and decaying as if suffering from aggressive cancer and multiple organ failure.
The lost numbers are their own horror. They are ostracized from Cronos and are usually doomed to be continually experimented on in agonizing pain for the rest of their existence unless they are deemed useful for tasks.
In the light novels, Cronos once managed to grow some of the organism that the Guyver is without its control medal. The result is akin to the 1982's The Thing, not only can it shapeshift, but it will absorb any and all biological organisms that it touches. Unlike that creature it doesn't seem to gain intelligence, which might explain why the Sho's arm based clone was only single minded in hunting him instead of absorbing all life in its path.
Aptom is also similar to both the Bio-Booster Creature and The Thing after his body was modified by Hamilcar Barcas, like having the ability of genetic memory at a cellular level even when split up into multiple bodies and absorb the biomass and powers of Zoanoids. Unlike the Guyver Bio-Booster Creature, he is intelligent enough to mimic humans and Zoanoids, isolate them, and then eat them alive. However, his cells can be infected by a virus that counteracts these abilities. It's a relief Aptom became a good guy as the series progressed.
