Hazards are rife in the Happy Tree Friends universe, they range from natural events to specific objects.
Non-anthropomorphic animals have caused the deaths of characters in numerous episodes. Usually these attacks are done on purpose, but at times something may be caused accidentally that would make normally friendly animals turn vicious (such as Whistle when he hears a whistling sound, or The Baboon when a camera flashes).
Cacti (plural for cactus) are tall, green, spiked plants. They appeared in the episodes Just Desert and And the Kitchen Sink. In the aforementioned episode, Pop made the assumption the Cub fell into a cactus patch, and he worked his way through, scratching and pricking himself. When he made it to the other side, he was shocked to discover that there was a sidewalk he could have taken to go around the cactus patch.
Flesh Eating Flowers
These are purple flowers that appeared in Idol Curiosity. They are capable of removing and digesting flesh, bone, muscle, and internal organs. One flower nearly bit Flaky on the face and sheared a butterfly to bits. When Sniffles dragged Flaky through a thick bush of these flowers, all that was left of Flaky when they got out was one of her arms, with a uprooted flower still snared on it. Sniffles was missing parts of his skin and had bite and scratch marks all over his body.
A large meteor is seen flying towards the earth in Better Off Bread. Splendid manages to stop it by flying directly at it with his fist out, this only causes the meteor to break into smaller pieces resulting in a meteor shower that kills Toothy.
One can be seen at the bottom of the ocean in Sea What I Found. The heat from its lava melts Lifty and Shifty's gold and causes the submarine to explode.
Only seen in Mirror Mirror. An active volcano causes panic in a city when Splendid throws a large rock on the top. This fixes nothing as the volcano blows the rock away when it erupts.
In Ski Ya, Wouldn't Wanna Be Ya!, Flaky accidentally causes an avalanche with her screaming which may or may not have killed Giggles and Petunia.
An oil spill is caused on a shore in Better Off Bread. The oil has spread over two birds and a seal.
In Remains to be Seen, Flippy is seen driving a truck with barrels of waste in the back. Where and how he got it is unknown. The waste is shown to be capable of bringing dead characters back to life.
The Cursed Idol
- Main article: The Cursed Idol
Considered as the pinnacle of danger in the Happy Tree Friends world, an object specifically created to cause death and destruction in some of the most intricate and gruesome of ways.
- Main article: The Demon
This squid-like creature was released after Pop read a spell in a cursed book. It possessed Cub and killed Petunia. Lumpy managed to defeat it by devouring it.
A large, mythical, Japanese, monster first seen in Wingin' It, it eats Flaky at the end of the episode.
Considered hazardous only to Splendid, and possibly Splendont, its radiation causes Splendid to feel weak and sick, extreme doses can cause extreme sickness, fur and skin loss, and is possibly lethal. It is Splendid's weakness like the Kryptonite is Superman's weakness.
- Main article: Pod Lumpys
It appears at first as a regular meteorite when it explodes in the air and appears to be a green seed. Apparently, if one touches the seed before planting it, clones of whoever touched the seed quickly grow from a plant.
The sentient earthquake is a crack that appeared in Idol Curiosity. It followed Sniffles and his partners to retrieve The Cursed Idol. It is probably something sent by the Cursed Idol to get it back to its rightful place. It swallowed Giggles. and it tried to kill Sniffles. Only Sniffles runs away and at the end of idol curiosity the earthquake kills Sniffles cutting him vertically in half.
- Main article: Fliqpy
Flippy suffers from PTSD (Post Traumatic Stress Disorder) from his days in the war. Whenever he sees/hears something that reminds him of warfare, he will flip out and kill other characters. He seemed to have gotten rid of this problem in Autopsy Turvy but was killed shortly afterward. It was later revealed in On My Mind that he got it back.
- Main article: Mr. Pickels
Mr. Pickels is known for killing other characters and framing Lammy for it. Lammy is the only character who can actually 'see' Mr. Pickels, while everyone else sees him as an ordinary pickle. Thus whenever Lammy tries to stop Mr. Pickels, it would appear to another character that Lammy is actually the one responsible.
- Main article: The Ants
The Ants have often evaded Sniffles' schemes and got revenge by sadistically torturing and killing him. Tongue in Cheek was probably the most torturous episode so far, bringing Sniffles to extreme tears, whimpering and begging. This is also the longest and most torturous death that Sniffles (and possibly any other character) has endured. Sniffles is the only character to encounter or be killed by The Ants.
Most of the series' deaths have been accidental, but sometimes a character has murdered on purposely, most notably in Happy Trails Pt. 2: Jumping the Shark when Flaky was murdered by Handy, Sniffles, Flippy, and Lumpy. Suicide attempts have also been seen, such as Petunia in Wishy Washy.