There are several gruesome scenes throughout the series.
- New Blood: It's not surprising if any kid back in 1999 that saw the series for the first time has been scared by the death of the baby cynodont who wandered too far and the look on the Postosuchus' face as she dies (she's drooling, and her eyes are blood red).
- In a deleted scene in the US program: the couple of adult cynodonts eat their own young to have more possibilities to escape predators. Since there isn't any fossil proof about this behaviour, was it really necessary to show it?
- "Cruel Sea". Just..."Cruel Sea". It's not surprising if it didn't make a whole lot of people not want to go anywhere near any coastlines for a while... in particular, that part where the bitten-off Opthalmosaurus tail slowly sinks to the sea floor is what did it for many people.
- Liopleurodon is the definition of a Sea Monster, managing to make the shark from Jaws look like a sardine in comparison. Its size in the series may have been greatly exaggerated (Liopleurodon is actually 20 feet long, but the show depicted it as big as 75 feet long), but that still doesn't make it any less scary (in fact, you could probably say that the size exaggeration was actually intentional).
- It doesn't help that his design makes him look as though he has a perpetual Slasher Smile.
- The Liopleurodon's death, seeing as after he's beached he's slowly crushed underneath his own weight.
- A deleted scene from the original: the dead tyrannosaur embryo out of the broken egg.
- Worse still, someone apparently thought it was a good idea to restore this scene in the DVD version.
- The scene just before the meteorite hits: everything just seems to stop. The baby T. rex look out into the distance. The Anatotitan and Torosaurus herds look up at the sky. The Dromaeosaurus runs for cover. And then the shockwaves begin...
- The Koolasuchus from "Spirits of the Ice Forest". A huge carnivorous amphibian that acts something like a crocodile.
- The giant ants in Walking with Beasts which devour the chick alive, depicting how the chick struggles to hatch from its egg as the ants swarm all over body and then the skeleton of the chick when the mother returns, caused many viewers to hate not only the entire ant lineage, but even ant-scientists and ant-lovers since watching this scene. Zoologists and environmentalists have to thank Walking With a lot.
- From the same episode, the giant flightless bird Gastornis killing its prey. It does it by shaking it to death while giving off strangled shrieks that are almost growls. The death is so drawn-out and just plain savage that it manages to be truly brutal even though it's Bloodless Carnage - though you do hear the Sickening "Crunch!" of its neck vertebrae being snapped.
- Some scavengers in the series seem to like to eat the eyes of the corpses. And the female Dimetrodon loses an eyeball after a fight.
- The agony of the armoured herbivore Scutosaurus killed by the mammal-like gorgonopsid in WWM: you can see the blood of the former gushing out of its neck!
- Walking With Cavemen may as well be retitled "Walking with Nightmare Fuels" as well, it's full of these from the start to the end... especially about the exaggerated realism of some death scenes.
- The fact that some of our ancestors in the program are portrayed with a rather... grotesque look makes this program even more scary. That means that we are descendants of Nightmare Fuels. Every person that you see every day, including you, is descended from those Nightmare Fuels. So we are surrounded by Nightmare Fuel every day. Come to think of it, Walking With Cavemen could also count as Fridge Horror.
- Our earliest ancestors shown, Australopithecus afarensis, look like something right out of a horror film. Behold!
- Maybe these ancestors were not so Nightmare Fuelish in Real Life... but producers thought well to make them as scary as possible because of the umpteenth Rule of Cool example. However, see the australopithecine's look in WWB, they are even nice-looking... It seems many WWD continuations really like to play straight the Darker and Edgier trope (not only Walking with Monsters). Anthropologists often say if Neanderthals would be alive today and clothed, they'll pass unnoticed in our modern cities.
- And even then, the books based on each series are worse, and employ vivid descriptions of other deaths unseen in the series. It's true Nothing Is Scarier.
- The distressed sounds the Iguanodon makes and its look of horror when it's being killed by the Utahraptor.
- The whole premise of Sea Monsters is a group of time-travelers trying to dive with and study very dangerous prehistoric creatures, so there are naturally quite a few scary moments, even though the humorous tone tries to keep it light. Special mention goes to the break between Part 2 and Part 3 where it looks like Nigel has been eaten by a C. megalodon, and The Stinger showing mosasaurs approaching the sonar screen as the crew sleeps.
- From the 3D movie there is the forest fire and the simultaneous Gorgosaurus attack.
Patchi: What's fire? Does it eat meat?
- The following exchange during the forest fire, one of the few times the dialogue isn't too forced.
Alex: It eats everything! RUN!
- Scowler getting Drunk with Power after becoming leader of the herd qualifies as well. When he leaves Patchi to die after saving the herd from a frozen that he himself lead into, it looked like he had become a sociopath.