- The show's intro features a Rogues Gallery montage, where Tarzan clashes with La and her leopardmen, Tublat and Colonel Staquait. There's also a brief glimpse of Mabaya, Hista, a leopard and a Tyrannosaurus rex, as a reminder of how dangerous place the jungle is.
- The first episode of the series shows Tarzan nearly dying a slow painful death from being bitten by a highly poisonous spider. Not some climactic battle, not against some awesome enemy, or a heroic sacrifice befitting a peak human specimen. Just a tiny arachnid bite nearly did probably him in if not for help from Professor Porter and is a blatant case of Reality Ensues that living in a jungle full of all sorts of deadly creatures will get you killed eventually on your own without aid, even if you're badass like Tarzan.
- In the episode, Tarzan also hallucinates because of the spider venom in his system and runs in fear and nearly falls to his death due to a horrible vision of Clayton alive again trying to murder him with a rifle. Even long after the man's death, Clayton is still a source of fear for the King of the Jungle!
- Earlier in that episode, Terk fell into the dead tree stump where the spiders lived when she got out she was covered in spiders! Tantor saw this he panicked, he grabbed her, and dunk her in the pool of water to get the spiders off and Terk even flicked one spider off of her spiders assuring Tantor that he had nothing to fear about spiders. But however, Tantor was right to be afraid and he even saved Terk's life because how poisonous those spiders were! Being bitten by one spider is bad enough but being bitten by thousands of spiders is even worse! It's the good thing Tantor dunked Terk into that pool to get those spiders off of her or otherwise she would've been the one who got bitten and died from a lot of venom from those spiders!
- In Lost Cub, the episode highlights how Leopards in general like in real life are straight up monstrous predators in the jungle and are still as every bit of dangerous to Tarzan as Sabor. When Tarzan and his friends had to venture into Leopard territory to return a lost cub, they were nearly mauled to death if not for timely help from the cub's mother.
- Before that, the cub upsets the local baboon youngling and brings the whole group to attack. Terk was chased back to the treehouse trying to protect the cub with baboons literally swarming all over it trying to kill them both until Tarzan arrived and scared them off.
- Tublat. He's every part of the Killer Gorilla trope Up to Eleven and his personal history is the stuff of nightmares. He was once a member of Tarzan's gorilla family but was the animal equivalent of a violent psychopath who went around attacking other members of the family until Kerchak tried to stop him. Kerchak initially won, but Tublat struck back and nearly killed Kerchak if not for some timely intervention by a young Tarzan. Tublat was banished and lived his life in a cave, which is littered with the bones of large animals (it is ambiguous whether Tublat has killed and eaten those animals or not). When Tarzan's ape family unknowingly went to Tublat's cave seeking shelter from a storm, he went about quickly and silently kidnapping all of the gorillas like some horror movie monster and throwing them in a hole to force them to follow him or die from starvation. Furthermore, Tublat is a straight up Lightning Bruiser, far too strong for even Tarzan to fight evenly and would have nearly killed him if not for Tarzan flinging himself and Tublat into a nearby river so Tublat could drown.
- He later appeared again in Enemy Within where it's revealed he survived his drop off a cliff into a raging river, found another ape family, and killed their leader to take it over and use Gobu, one of its members, to lure in Tarzan under threat of death or mutilation of Gobu's family members.
- Queen La herself is nothing to scoff at in the horror department. She's an ancient sorceress looking for a mate and normally that wouldn't be bad if not for her nasty tendency to kidnap and sacrifice people who displease and vaporize her leopard men minions for the slightest mistake. When she tried to execute Professor Porter for being an unsuitable mate she fell in mad love with Tarzan for rescuing him and then tried to murder Jane to keep Tarzan for herself. After her attempted murder was uncovered, La tried to kill Tarzan for rejecting her.
- Her next appearance involved a rebellion from her leopard men that ended with her literally melting into ashes after her staff, the source of her powers and immortal life, was destroyed while cursing Tarzan and his friends. Before that she tried to feed Tarzan and the leopard man who led the rebellion to some tentacled "THING" living under her city with a lair littered with the skeletons of men who displeased her in the past.
- Her final appearance, she came back as a literal Eldritch Abomination ghost possessing bodies to get to Jane to use as a new body until she managed to possess Tarzan and tried to kill Jane while using Tarzan's body.
- Colonel Staquait is a fairly menacing example of a Lawful Evil Implacable Man in the series, considering he hunts after Hugo and Hooft all for personally disobeying his order to burn down a village of women and children. He has a French Guillotine brought to the jungle just to have them decapitated as punishment and only left when he was convinced they died. In his next appearance, he found out Hugo and Hooft survived and came back to capture them and eventually Tarzan for stopping him last time, taking them to a Hellhole Prison where he tortures the prisoners and nearly would have executed Tarzan and his new friends unabated if not for a clever ruse by Jane and Dumont.
- Mabaya. It is implied that he was a perfectly normal elephant like Tantor before he became a rogue, but then he went through Sanity Slippage and turned into six tons of pure rage with red, pupil-less eyes that charges at everyone in his path.
- Tantor undergoing Sanity Slippage due to thinking he contracted rabies and was going rogue (i.e. turn into a monster similar to Mabaya) in The Rogue Elephant.
- The diseased hippos in The Poisoned River. As in Real Life, Hippos are depicted as vicious brutes who nearly capsize Tarzan's boat, eat Professor Porter, and force Tarzan to flee.
- Pellucidar. A hidden biome within the Earth's crust that contains all sorts of dinosaur predators and methane gas geysers. It's Death World to modern animals and Tarzan is especially wary to go there until prodded by his friends. The first time Tarzan went there he barely escaped with his life and one velociraptor escaping there into the jungle in The Beast from Below was enough to put the whole jungle on edge.
- Hista. A python that's large enough to swallow a gorilla whole, and is a very active hunter. There's a good reason he's treated as The Dreaded in-universe by the gorillas. His appearance, with red and black scales and massive fangs adds some extra nightmare factor.
- The animals going insane in The Jungle Madness due to a subsonic frequency from the trading post radio station. All animals including Terk and Tantor are yelling for Tarzan to stop the ringing and try to kill him and Jane in a berserk frenzy. Jane and Tarzan all the while try to find Professor Porter with an Apocalyptic Log he wrote detailing the events where he was chased by woodpeckers popping out of flowers like Chestbursters from Alien and being attacked by animals all the while in an effort to find the cause.
- The events of The Outbreak are fairly unsettling a real life situational sense. Tarzan confronts a group of sympathetic loggers who are cutting down trees in the jungle. Unfortunately, as the Professor warned would happen, their logging has dug up a particularly deadly microorganism deep in the soil into the air, getting the loggers and the director's daughter sick with a lethal disease. This isn't a fictional case. Real life developers and workers have gotten sick in foreign lands by recklessly digging up disease carrying toxic substances in the soil.
- Robert Canler can be unnerving to watch considering he appears as dashing Officer and a Gentleman but is probably a textbook example of The Sociopath with few scruples other than genuine care for his oldest friend Jane. Tarzan immediately sees through Canler's act and warns Jane not to trust him but nobody believes him. It turns out Robert gave Jane a music box before she left London to eventually meet Tarzan which was actually a stolen British code machine that Robert slipped to Jane to get British intelligence off his trail. He was actually a double agent and spy who planned on selling the machine to Britain's enemies for a large profit (implied to be the Germans during World War I) and only went to Africa to get it back when Jane hadn't returned from Africa. He then tried to kidnap Jane to leave no witnesses, but was foiled.
- Considering the punishment for high treason in British during World War I being the gallows, it's clear that was the last time Jane ever saw her oldest friend.
Nightmare Fuel / The Legend of Tarzan
Befitting the dangerous nature of the African Jungles, the animated series expands upon a variety of nightmarish situations that comes with living in the wilderness unprotected from both monstrous animals and variety of supernatural threats.