Tommyrod. Good God, what a monster The man is a walking insect nest, who can do some downright disgusting things with his bugs. And don't get started with his rows of razor sharp fangs
Grinpatch. Insect-emulating mutated abomination, with a taste for others' despair. And he means it literally. Only fails to be the most disgusting and nightmarish character in this manga due to being completely overshadowed by Tommyrod.
Zebra can make it sound like he's standing right behind you even when he's tens of kilometers away.
When the ancient Nitro first appears behind Komatsu. And again when it opens its beak-like mouth, which is absolutely filled—not just lined, but FILLED—with rows and rows of horrible pointed teeth. Nitros in general, being the inspiration for the GT Robots.
Losing a bet in the Underground VIP Area of Gourmet Casino means you will forget the taste of every food you have ever eaten.
The huge monster that represents the Four Beasts in the legends describing them is terrifying. The image of countless humans writhing in its jaws...
The ending to Chapter 208. Oh God, the ending. Mood Whiplash at its finest. Anymore would spoil. Turns out to be just a nightmare.
The Pierced Nitro in 222 and 223...
The Giant Parasite in 224. To quote Sunny: "GROOOOOOOOOAAAAAAAASSSSSSSS!!!!"
Toriko's state after his battle with Stayjun. Remember how he looked after battling Tommyrod, minus one arm and generally beat up and covered in his own blood? HE GOT OFF LIGHT THEN IN COMPARISON! After fighting Stayjun and managing to inflict a mortal wound with his Routine Energy, he's collapsed against a cliff...has only one arm left, is covered in burns and the blood is used as a censor for his worst injuries.
Just about everything about Joa. The fact that he can erase and replace a person's personality, that he can turn your best friends into your worst enemies, that he casually rides on a Phantom Beast with a Capture Level of 295, or that he apparently is even STRONGER than characters like Setsuno, who are very much regarded as the strongest fighters of the Human World. Oh, and he also won the Cooking Fest 200 years ago, and still managed to erase his name from history. Not to forget that he is in cahoots with the secret organization NEO, who seem to have their agents planted just about everywhere, implying that Joa may be one of the, if not THE, most knowledgeable characters in the series.
From episode 113, more Accidental Nightmare Fuel than not, the Zemen noodles sound remarkably like a human being when massaged, which is very surprising coming from a non sentient food
Horse King Heracles was intimidating when it first showed up, sure... thenitdidthis.
Toriko's Blue Oni. 'Nuff said.
The ending of Chapter 292 Teppei appears, rips Komatsu's heart from his chest and CRUSHES it.
In chapter 299, the monkeys that attacked the heroes are all dead (except one), their heads smashed into the ground while their bodies are still upright in grotesque headstands. The worst part? They did this to themselves to avoid the punishment they would have faced from their master for hunting the heroes without its permission.
The Sandoriko Plant. While it looks like a Pirahna Plant, what it's pollen does to people isn't comedic. The pollen of a Sandoriko Plant causes a severe allergic reaction which forces every drop of liquid in their bodies to come pouring out of the Four King's eyes and nose. That was just pollen from a genetically weakened version of the Sandoriko Plant. The real plant, which is many times larger and reacts to any stimulus, would have killed the Four Kings instantly. Every beast in Area 7 is terrified by the mere sight of this plant, even the Blue Nitro. Ironically though, despite almost killing the entire ecosystem, the Sandoriko plant prevented the Blue Nitro from harvesting PAIR, which would have devastated the ecosystem even more than the plant itself.
Chapter 303. Monkey King Bambina maims all of the Four Kings save for Sunny. Toriko loses an arm, Coco loses his leg, and Zebra's head is twisted right off.
Thankfully they were all Poison Dolls made from Coco, only Toriko lost his arm but the rest survived. Doesn't make it any less scary though, especially when the next chapter revealed that the Monkey King was playing with them. What's more when he sneezed, he literally blew away the group some distance completely by accident!
The Eight Kings as a whole. Just one of the Four Beast's "limbs" - creatures with Capture Levels varying from 100 to 150 - are capable of annihilating the whole of Humanity on their own, the Eight Kings reign over the Gourmet World and all have Capture Levels with at least 6000, and their strength makes defeating individuals as strong as the Heavenly Kings literally an act of blowing air in their direction (which Toriko learnt the hard way when against Heracles). The smallest of them, Bambina, is a human-sized monkey. The largest of them is the Mother Snake, said to grow to the length of the circumference of the Earth - the Toriko Earth, which has a circumference of 220,000 kilometres.