This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Duke Nukem 3D
Duke Nukem 3D features naked women trapped in alien plant matter throughout the game, who mutter "Kill me" in a desperate tone when talked to; it's a bit creepy, but soon you get used to it. All you can do is either kill them or leave them to their fate. Even worse is the poor woman in the intro in Episode 4: The Birth. As if being impregnated and giving birth to the alien's new Queen isn't bad enough, there are alien troopers surrounding her, watching with joy as she screams in agony and presents them with their abomination of a ruler.
The Assault Commander. "Suck it down!" "Boom!", Duke gets reduced to Ludicrous Gibs. An even scarier Demonic Spider is the Protector Drone. Horrific appearance and sound, loves to hide in dark areas where its glowing red eye is the only thing visible, moves like grease lightning and attacks with shrink rays.
This example is somewhat of a mix between Nightmare Fuel and Fridge Horror: You cannot see any Pig Cops in the Lunar Apocalypse episode, which makes sense In-Universe, since they are LAPD cops mutated, and LAPD doesn't exactly operate in the outer space... You can find one Pig Cop, however, in level 8 (Dark Side), who is lying dead on a table with surgical equipment nearby...why (and what for) were the aliens experimenting on a mutated human being?