This game series is literally filling with horrors and we have to be careful.
''VideoGame/DiabloII'' and ''VideoGame/DiabloIII'' have [[NightmareFuel/DiabloII their]] [[NightmareFuel/DiabloIII own]] pages.
* Sure the creepy dark seems pretty standard dungeon-crawler fare, but when you start reading into the lore of the world, and asking about some of the quests...
* The Zakarum Cathedral of Tristram, dark and endless and full of all kinds of monstrosities.
* The [[http://www.diablowiki.net/Diablo_I_Manual#The_Darkening_of_Tristram Darkening of Tristram]] as described in the ''Librarius Ex Horadrim'' from the Diablo I Manual, particularly the vivid description of the possession of young Prince Albrecht by Diablo himself, and the horrific effects it has upon both the poor kid and the surrounding vicinity of the labyrinth.
* Special mention goes to "The Butcher", a huge, fat demon who makes his residence in Tristram's church. In a room completely filled wall-to-wall with corpses [[BeefGate somewhere above the first floor]]. He killed a fairly large regiment of soldiers by himself, and [[NintendoHard he'll probably kill you without a problem, too]].
** "Ah! Fresh meat!"
* Of course there's [[spoiler:the ending too]], although in particular when you [[spoiler:defeat Diablo as a Rogue. Her scream in the final FMV sequence is nothing short of genuinely chilling]].
* [[http://www.youtube.com/watch?v=k9pqRt38ms0 This soundtrack.]]
* [[spoiler:Diablo has possessed your character.]]