This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / World War Z
From the horrific images of armies crumbling under endless tides of graying, mindless ghouls to the insane tale of the French military's battle against the zombies in the Paris Catacombs, World War Z has no shortage of chilling apocalyptic imagery. And that's not even getting into the hair-raising, often tragic tales the various survivor interviews weave. And the bomb that tears your lungs out through your mouth. Which actually exists. Too bad zombies don't need lungs.
North Korea. Most of the first half of the book is horrific, but North Korea in particular...it's the fact that even twenty years on, nobody knows what happened to them all. From there it has to make you wonder what would happen if they areall zombifiedin hiding, and what would happen if they ever got out.
This fanfic does a good job of giving you the idea of what happens to the North Koreans. The poor man left in the bunker....
It might not be too bad. 24 million NKoreans zombies at most, minus all the ones no longer viable, plus the fact that we know what to do now... There'd be a bit of initial devastation in the neighboring countries, but it's certainly containable. Probably best to start walling the place up now, though.
They already did it by themselves.
Even if the North Koreans aren't infected, it'd be pretty nightmarish. At least living on the surface they have some hope of escaping across a border or growing some food for themselves; imagine how much worse it'd be underground, where the dictator controls all the food, water and air. Especially if the stockpiles start running low before the ones in charge are ready to leave...
The fanfic linked above nods to this, when the person being interviewed muses about the possibility of even some North Koreans remaining alive in their tunnel complexes. He begins to muse about what they must be doing for food after having been underground for over a decade... before deciding that he'd rather not think about it.
The story of one of the men that has to go down onto the sea floor to find any large groups of zombies that are still wandering around under the sea. He comes across a wreck from the war, goes down to check it, and falls down through the floorboards, into a room full of zombies. They all grab at him with their arms but he's saved by the fact that he's wearing one of those old-timey diving suits.
Comes with a Suspiciously Specific Denial on the interviewee's part that implies recurring nightmares. "If I ever had a recurring nightmare, and I'm not saying I do, because I don't, but if I did, I'd be right back in there, only this time I'm completely naked... I mean I would be". In-world example?
Divers working on offshore rigs were occasionally ambushed by zombies. Some were torn apart, others were killed by the bends as they tried to escape.
The story of the war against zombies in the sewers of Paris. Difficult to breathe, unable to see, never knowing when a zombie will grab you and drag you to a watery grave . . .
North Platte being invaded by a horde of zombies.
The survivors in Canada turning to cannibalism out of desperation.. The interviewee did say the soup smelled good, though... "By Christmas Day, there was plenty of food."
That entire segment counts. It's downright horrifying to see how a camp of normal people managed to devolve into desperate, paranoid psychopaths, starving and freezing to death.
Alang, India. People attempted to swim out to ships and could see as people right next to them were dragged under by submerged zombies. Many were trapped between the zombies coming from inland and the underwater ones.
The truckload of infected refugees heading to Kyrgyzstan.
The parents killing their own kids in the church in the Midwest.
The fact that the scene is described (or, more accurately, acted out) by someone with the mind of a four-year-old makes it worse. Poor Sharon...
Then there's this bit, which makes you glad this is a transcript instead of an actual recording:
The book before it, The Zombie Survival Guide, is even worse.
The Chapter on a total zombie apocalypse kept one up a few nights. Imagine being the last known humans in a world filled with undead. It combines two things that will freak anybody out: Complete isolation/loneliness and zombies.
The part of the guide that has recorded events of zombie contact had some pretty scary ones - the one where an entire ship and the slaves chained in lines it were zombies pretty much lampshaded it by explicitly telling you to imagine the horror of the possibility of being a slave on the far end of the ship while one on the close side was bitten, killed and reanimated to bite the slave closest to him and repeat the process, watching undeath approach you with each person...
Not to mention wondering if the person on the other side of you is going to figure out their only alternative is to kill you before the infection spreads that far...
Actually, given the time-lag between biting and turning, most of the slaves would've died of thirst before the infection reached them. More likely, a single zombie from the crew managed to enter the hold, but was physically unable to feed for some reason (e.g. one of the living crew might've driven a blade through its throat and left it, blocking its esophagus), so just kept biting one victim after another.
Or the order of Samurai devoted to fighting the undead who required their new members to spend the night locked in a room full of gibbering severed heads.
Though the book acknowledges that the heads probably weren't actually making any noise, given that severed heads would have no lungs to produce sound with. Heads that are silent except for constantly snapping jaws aren't a huge improvement, though.
In the back of "The Zombie Survival Guide" there are blank pages that are laid out like journal, with places to fill in the place, time, location, distance from the person, specifics and the action taken, so the reader can keep track of attacks near them...making it even more like a real survival guide.
Brooks has stated that one of his fears is that of a zombie, a creature that comes for you for no reason, could not be reasoned with, and unstoppable. He neatly conveys this to the reader through one of the stories, where it's described that no human country can be 100% devoted to war (due to elderly, babies and the disabled) while zombies had no such handicap.
The people receiving infected organs via transplants and transforming into zombies days, weeks, even months later.
The implication of all those women being infected after receiving donated eggs and/or sperm is even worse.
Are you thinking that those women got pregnant with zombie fetuses? Don't worry, according to the zombie survival guide, all zombies are sterile so none of those women could have gotten pregnant. But they all died or turned into zombies though.
The baby zombie, still tied up in the carrier, snapping at the woman as she passed by during the crashed pilot's story.
"Closure, Limited", a short story based in the same canon as World War Z but that Brooks published for an anthology, has him interview a company that attempted to find loved ones that had become zombies, "pacify" them, and then return the remains to their living descendants for proper burial. However, the impossibility of some of these assignments has led to them taking random zombies and giving them post-kill plastic surgery to make them look more like the victims being sought. The ending has the owner of the company give Brooks an opportunity to kill a zombie himself, and the closing scene is of Max leveling a pistol at the zombie's head.
Even putting aside the zombies, the chapter that points out that something as ubiquitous and simple as root beer depends on international trade can be nightmare inducing if you consider that it wouldn't take a zombie apocalypse to shut down that kind of thing. In the civilized world, nearly everything you depend on, down to basic food, is the result of national or international trade. Bread, milk, meat. A disaster that takes down infrastructure will mean within days people will be starving. People starving becomes people rioting, and it will only get worse when processed foods just run out. Look at your community and think about this: Almost nobody around will know how to do something like process an animal for meat. If there's even meat to be found.
The film suggests that North Korea survives by pulling out the teeth of all its citizens.
The ex-CIA agent pulling out one of his own teeth in front of Gerry to demonstrate.
Segen getting her hand chopped off. The fact that not much blood is shown somehow makes it worse, since the camera instead focuses on her reaction.
The airplane sequence. Good grief, the airplane sequence.
The roof scene - the fact that the lead zombie is Tommy's father - a man who moments ago was quiet-spoken and concerned about his family - turned into a mindless zombie trying to EAT his own child.
The zombie invasion of Israel is animalistically efficient.
The way the zombies are animated. You know the use of the word "tides" up in the novel's section of the page? It's taken to a literal conclusion here. The zombies, in large enough amounts, don't swarm. They flow. They become an unholy tidal wave of flesh that tumbles after any healthy human being in range.
The zombies that manage to climb over the Israeli wall throw themselves from it in a rain of living corpses. The ones that survive keep crawling after humans even with their bodies hideously mangled and broken.
The fleeing garbage truck plowing through the streets. Not just because of the damage, but there are usually guys hanging off the back to quickly gather trash. Can you imagine being the driver, watching your buddies being ripped off and eaten?
What is the most terrifying aspect of the transformation from man to zombie is this: You're conscious for every second of it, and it is clearly painful. Those twelves seconds? There's no doubt that they feel like twelve thousand years of absolute agony. Perhaps worse is the psychological aspect of it: You're fully conscious and aware as the virus takes over your body and mind, and overwrites you, transforming you into nothing more than a vehicle to transport the virus to other hosts.