Similar to crocodiles only dwelling on land, monitor lizards are the lizards most likely to be cast as antagonists in animal fiction. They are also common foes in jungle settings.
One reason why monitor lizards get such a bad rap is from their large size and strength, as well as their rather intimidating appearance, since they stand as the largest lizards in the world and are capable of taking down deer and water buffalo. Their habit of flicking out their tongues a lot (they "taste" the air to, well, monitor it), looks like a Maniac Tongue if the lizard is somewhat anthropomorphized.
What also doesn't help their reputation is their diet, as they're often seen as scavengers due to the amount of carrion they eat. In fact, for a long period of time it was assumed that this reason why they had such nasty bites, where the deadly bacteria they picked up from carrion was responsible for taking down prey. However, later studies conducted in the mid-to-late 2000s debunked this theory, with it instead being revealed that monitors are among the few lizard species with a venomous bite. The venom further adds to their villainous reputation, because Poison Is Evil.
In fiction, monitors will usually be a generic kind. If a real-life species does get chosen, it usually be the Komodo dragon; this is partially because Komodos are the largest kind of monitor and look rather intimidating and partly because it's the only species audiences will be familiar with. Even so, Komodo dragons are a Seldom-Seen Species especially compared to geckos, chameleons, iguanas, and even frilled lizards.
Komodo dragons are generally portrayed as powerful, dangerous predators; fitting with their intimidating appearance and size. "Lesser" monitors, conversely, are often portrayed as sneaky, thieving slimeballs, with a particular taste for eggs. Obviously this adds to their negative portrayal, since eggs are effectively other animals' kids-to-be.
Subtrope of Reptiles Are Abhorrent. For monitor lizards pretending to be dinosaurs, see Slurpasaur. Contrast Lovable Lizard, for more benign lizards. See also Snakes Are Sinister and Never Smile at a Crocodile for other villainous reptiles, as well as Stock Dinosaurs for their ancient cousins the Mosasaurs.
- Budzo, the Big Bad of Adventures in Zambezia is a vicious monitor lizard with a taste for birds' eggs who was responsible for killing the protagonist's mother.
- The Rescuers Down Under features Joanna, a goanna who serves as Percival McLeach's Right-Hand Attack Dog who has a massive appetite for eggs, including the eggs of the giant eagle Maharute. Also provides the page image.
- FernGully: The Last Rainforest features a blue and red monitor lizard that sings an entire musical number about wanting to eat one of the protagonists. However, when not hungry, he turns out to be a pretty nice guy.
- Komodo dragons act as the Shark Pool in Skyfall; whilst Bond escapes them, they end up devouring an unfortunate Mook.
- The thriller film Komodo is about a colony of Komodo dragons living on an island in North Carolina, killing the humans that visit the island.
- According to supplementary material the raptors in Jurassic World have monitor lizard DNA mixed in, presumably explaining their lack of feathers.
- There's also the park's Mosasaurus, effectively a sixty-foot-long marine monitor lizard that eats great white sharks. It's actually a downplayed example—the only time it kills human is by accident, and in the climax, it proves instrumental in defeating the Indominus Rex.
- In Redwall, most Reptiles Are Abhorrent, which holds true for the monitor lizards of Sampetra, who serve as shock troops for the pine marten Big Bad of The Pearls of Lutra.
- Subverted in the Komodo dragon chapter of Last Chance to See by Douglas Adams and Mark Cordwaine; unsurprisingly, since the point was to raise awareness of the Komodo dragon as an endangered species. But when Adams and Cordwaine arrive there, they're surprised to find a tourist trail where a dragon eats a live goat that's been staked out for it. The tourists talk in fascinated horror about this monster, and how easily it could do the same to them, but Adams's own view is that the lizard is just being a lizard, and if you want to blame someone for the fate of the goat, then Humans Are the Real Monsters.
- Jessie: Subverted, by Mrs. Kipling, Ravi's pet Asian Water Monitor. Whilst she is aggressive and scary, Jessie screamed when she first saw her, baring the occasional joke she's treated like just a big docile and slightly anti-social pet. She at one point saves Bertram and Luke, by eating a venomous spider that had invested the apartment.
- Monsters Resurrected has an entire episode focusing on Megalania, a 6-meter-long prehistoric monitor lizard from Australia, which, like every animal in the show, gets the Prehistoric Monster treatment. Another episode covered the monitor lizards' marine relatives, the mosasaurs.
- In Oceanian Mythology, Hi'iaka is tasked with bringing a young chief named Lohia'u to her sister, Pele (after the latter began to miss him after they hooked up at a party weeks before). Along the way, they face many adventures. In particular, Hi'iaka has to fight off giant monitor lizards with mana contained in her skirt. (Unfortunately for Hi'iaka, and more unfortunately for her friend Hopoe, this delays them quite a bit, and Pele gets jealous.)
- Conan Exiles: Komodo dragons can be found in the jungle in the south-eastern corner of the Exiled Lands (and, on some difficulties, the opening chamber of the Abyssal Remnant's dungeon), and are a threat about on par with the far-more-common crocodiles.
- The Komodo Bros. in Crash Bandicoot 2: Cortex Strikes Back are a Dual Boss, supposedly two of N. Brio's henchmen that try to block your path from helping Dr. Cortex.
- In Armello's World of Funny Animals, the monitor lizard Volodar is the High Priest of a Rot-worshiping Religion of Evil. He's Affably Evil, but preaches the glory of oblivion to all who will listen.
- The Lion Guard:
- Kenge is a rock monitor, who is aggressive, powerful and malicious. And who really, really dislikes being called little.
- Ora is a Komodo dragon who lives on the island the Lion Guard visits in the episode "Dragon Island". He's portrayed as a sadistic and ravenous predator, and at the end of the episode he makes an alliance with the evil leopard Makucha.
- Subverted with Komodo in The Secret Saturdays. He may be aggressive, but he's loyal and heroic. Played straight with his anti-matter counterpart, Komodo Monday, who's both entirely sapient and rather malicious.
- The short film Bilby by Dreamworks Animation opens with the eponymous bilby running from a hungry monitor lizard.
- Hey Arnold!: Zig-zagged with Helga's monitor lizard. The two seem to get along just fine, but the lizard itself is still an aggressive predator — something most notable when the school falls into chaos during Mr. Simmons's term as principal, during which the lizard can be seen in a hallway dragging a hapless student away.
- Littlest Pet Shop (1995): Delilah the monitor lizard is a recurring villain and constantly plotting to eat the other animals.
- In The Wild Adventures Of Blinky Bill (the 2015 reboot of Blinky Bill), Cranky the goanna is the tyrannical 'I Own This Town' mayor of Green-Patch and Blinky's constant nemesis.
- In My Gym Partner's a Monkey, the obnoxious hall monitor is a monitor lizard.
- Septarians from Star vs. the Forces of Evil are identified as lizards and bear long jaws most similar to those of varanids. While not all are evil a few have been prominent villains, most notably Toffee.
- George and Martha has a recurring character who is a Komodo dragon. He is not malicious but rather creepy, and has a habit of popping up right behind George.
- One episode of The Wild Thornberrys has Eliza wanting to meet a Komodo dragon. Once she and Darwin find one, it tries to eat them.
- In Total Drama Presents: The Ridonculous Race, the 'Got Venom' episode occurs in the Komodo Islands, and the first challenge is precisely to get some dragon venom. Owen gets temporarily blinded by the toxin, so he and Noah can't perform at their best and get eliminated from the race.
- Whether by accident or design, many reconstructions of theropod dinosaurs have monitor lizard-like traits; in particular, featherless renditions of dromaeosaurs look like bipedal Komodos. Special mention should go to the first reconstruction of a Megalosaurus, as depicted at Crystal Palace in London◊, which looks like a cross between a monitor lizard and a wolf.
- The last giant reptilian predator in the fossil record, Varanus priscus a.k.a. megalania, which went extinct as recently as 40,000 years ago, was estimated to be as big as 15 feet long, and weighing over 700 pounds. Also, it was believed to be venomous...
- The mosasaurs are Cretaceous sea lizards that are like flippered, shark-tailed monitors. There's evidence that they even had forked tongues.