Nightmare Fuel / Old Kingdom

• Considering that the series involves undead spirits hijacking and frequently reshaping dead bodies into Cronenbergian Body Horror as standard Mooks for the various villains, this comes as standard.
  • One particularly worth mentioning is a Dead Hand specifically described as having an elongated jaw and running towards a little boy who's to terrified to run away and just screams... until the jaws snap shut and the screams stop. Lirael's reaction, unsurprisingly, consists of Berserker Tears and her hacking the Dead Hand to pieces. And even while she does, the thing continues to hang on and bite.
• The first time we see Mogget unbound is possibly one of the most frightening things in the series, especially the sheer glee he takes in his description of how he's going to torture Sabriel to death...
  • When he's freed again in Lirael by the approach of Astarael, there's a dead silence in the pitch darkness... then what's described as a horrible, gloating chuckle. This lead in almost makes it worse, as the readers - who've seen Mogget unbound before - know what's going to happen, while Lirael and Sam have only heard about it. Dog's reaction adds to it.
  Dog: The Mogget is free! Run!
  • Mogget appears very briefly in "Terciel and Elinor", but his first encounter with Terciel, still a child, is incredibly unsettling, as they both sit atop a tree in the Abhorsen's House garden. The fact that he appears in his human dwarf form makes it seem worse, as he still moves like a cat, leading to several Uncanny Valley moments.
• Kerrigor lives and breathes this. Metaphorically speaking.
• The whole atmosphere in the Old Kingdom in "Sabriel" and "Terciel and Elinor" borders on Zombie Apocalypse. The Dead are commonplace and most settlements are shut in tightly at night, relying on water and fire to keep the Dead away. The Abhorsens help where they can but with no real royal Army to assist, help is few and far between, to the point where most people only know the Abhorsen as a folk tale.