Zachary "Zach" Varmitech is the archenemy of the Kratt Brothers and one of the four main antagonists of Wild Kratts. Accordingly, he has known the Kratt Brothers and Aviva since they were children in science camp and has since become a robotics expert. He commands a vast army of Zachbots who do whatever he says and kidnaps animals, so that he can put mind control devices on them to help with his construction projects (which seem pointless since he usually tries to build things far from civilization). However, his schemes always backfire because of the Wild Kratts.
- His first appearance was in the episode "Aardvark Town" where he's in Africa on an animal collecting trip and he's wanting to build a swimming pool to cool off. When he hears the Kratt Brothers are looking for the best digger in Africa (which was the aardvark), Zach orders his Zachbots to search all the holes to find it. When they found her and several other animals living the holes she dug, he put mind-control armor on the aardvark and had the the other animals chained.
- In "Flight of the Draco", Donita Donata hired him and his Zachbots as security for her treetop fashion show.
- In "Platypus Cafe" Gourmand invited Zach and Donita to his restaurant, where he's captured Chris trying to save Plato's eggs.
- In "Polar Bears Don't Dance" while Chris and Martin are following a mother polar bear and her cub (whom Martin names Poby), Zach is fascinated by how the cub looks like he's dancing. So he steals the cub along with a walrus calf and plans to them to dance for his audience at the opening of his new ice resort. However, when the Kratt brothers catch up to him the animal's mothers think they're in danger from each other and they engage in an intense fight which changes Zach's mind and decides to kidnap them instead and make them fight. So he tricks the brothers by luring them into an arctic storm.
- In "Honey Seekers" Gourmand invites Zach once again to his restaurant.
- In "Bass Class" Zach is seen relaxing on his yacht and is annoyed by Gavin's shiny trophy so he tries to take it from him. Chris tells him that if he wants a trophy he'd have to win one of his own, so Zach announces a bass fishing contest in which he cheats at multiple times. First he attempts to use live bait, then he has his Zachbot observer scare off the bass around Gavin's boat, next he has his Zachbots to go and buy a bass at the fish market, but Chris knows he's lying so Zach throws him overboard. Then he goes off to the spawning grounds to catch the father bass and finally creates bass-like Zachbots in order to win. Although he wins the contest, the bass-like Zachbots expose themselves to the protagonists, making Gavin, Aviva, and the Kratt brothers win by default.
- In "Mystery of the Weird Looking Walrus" he steals the Arctic Pearl and plans to give to Donita, only he ends up losing it in the ocean. So he attaches a bunch of mind control helmets to a bunch of walruses and makes them slurp up dozens of clams to find it. And when the Kratt brothers use Walrus Powers to stop him he traps them under the ice which nearly kills them.
- In "Tazzy Chris" Zach sees a headline ready the Wild Kratts will be tagging the endanger Tasmanian Devil. Seeing how scary they look he travels to Tasmania and steals them all to power he T-Devil security bots.
- In "Let the Rhinos Roll" Zach rounds up dozens of black rhinos and fits them out with body armor to create an army of living bulldozers so he can knock down trees and build a parking lot. In addition he gives a baby rhino calf (whom Martin names Nubs) a contact lens camera so he can spy on the Wild Kratts crew.
- In "Falcon City" Zach is first seen in the park trying to eat a a cookie, but pigeons eat it. Then when he orders his Zachbots to clean his building which is problems for a falcon family and their chick (Whom Martin names Fluff).
- In "Koala Balloon" Zach falls ill with a cold, so comes to Australia to get some Eucalyptus leaves to make Eucalyptus tea. But when he sees a baby koala in his potted Eucalyptus plant he orders his Zachbots to send it away on balloons over the Australian outback.
- In "Cheetah Racer" he was spying on Aviva from his hidden spy cloud, overhearing how they were having a race to see who was faster; a cheetah or a cheetah racer. He later decides to join the race, and cheats by using Blur the cheetah to power his all-terrain vehicle.
- In "A Huge Orange Problem" Zach's seen flying over the jungles of Borneo in his jet and decides he wants a side table made from black wood. So he orders his Zachbots to cut down all the trees until they find one with black wood.
- In "The Gecko Effect" while the Wild Kratts are looking for the secrets of the gecko's toe powers, Zach sneaks in the Tortuga to steal the Miniaturizer and then traps the Wild Kratts in a jar saying that he'll shrink some animals for them once in a while to play with.
- In "Quillbur's Birthday Present" Zach is in Africa once again on an animal collecting trip. And when he overhears the Kratt brothers making preparations for Aviva's birthday party, Zach steals some of the balloons and begins tying them to animals for his robots by airlifting them of the ground.
- In "Race for the Hippo Disc" Zach is seen canoeing through an African river with one of his Zachbots looking for a new animal invention, until he's attacked by an angry bull hippo and is saved by Chris and Martin. However, when he sees that they've lost their Hippo Creature Power Disc, he decides to let them lead him to it so he can unlock its secrets. Soon after, he's chased by Tusker the leader of the pod and gets stuck in a tree, after he gets down he soon gets his hands on Martin disc collection and even though they get it back Zach grabs a calf whom Martin named "Hipster" and threatens to take him if they don't hand over the discs. But Chris tricks Zach and gives him HIS collection case, only to find out its full of cookies.
- In "Creature Power Challenge" Zach attempts to ruin the brothers' fun by scattering a mud wallow everywhere, only to make things better for a rhinoceros and an elephant. Then he decides to ruin their fun by using Disrupto-Bots to activate past transformations to ruin Chris and Martin's Creature Power Challenge and to keep the crew from interfering he hacks into their frequency which prevents them from communicating with them.
- In "Shadow, the Black Jaguar" Zach wants a large black cat to use as the spokesmodel for his new line of Zachbots, so he sends his Zachbots to Central America to find one.
- In "Aqua Frog" after cleaning out his jet Zach is left with barrels of toxic sludge which he decides to dump into the river which nearly kills all the animals downstream in Frog Water Pond.
- In "Rocket Jaw Rescuer of the Reef" Zach roboticizes many parrotfishes and makes them munch off all the coral in the reef of the Caribbean Sea so he and Donita can sell coral themed jewelry.
- In "Skunked!" Zach is working on his new Bubble Bot, only to get a call from a spotted skunk, whom Zach thinks it the Wild Kratts at first. When he sees that they've left their Creaturepod and Buzz Bikes in the middle of the desert he decided to test out his new invention and go to the desert to steal their technology. Then he hears that their headquarters is infested with skunks he decides steal the Tortuga itself, but he can't get it out of hover mode so he decides to copy their secrets onto his flash drive and escape in his own ship.
- In "Gila Monster Under My House" after over hearing how strong a gila monster's jaw is compared to a power wrench, he decides to steal all the gila monsters in the desert and use them as living power wrenches.
- In "Mosquito Dragon" Zach tries to hack into the Wild Kratts data base, but no luck. Then after a mosquito bites him he gets the idea of creating mosquito robots to steal computer data from the Tortuga.
- In "Under Frozen Pond" Zach calls Donita and Gourmand informing them about their annual villains meeting to discuss getting rid of the Wild Kratts. So he decides to hold the meeting on top a frozen pond in the middle of the freezing wilderness. Unaware the Wild Kratts are right under the water below them, they soon resurface and return to their normal sizes the villains spot them and claim that the pond is their spot even though the Wild Kratts were there first. So they decided to settle this over a game of ice hockey, where Zach cheats twice but doesn't care. But they end up losing anyway and Zach states "This was a horrible place for a meeting anyway!"
- In "Osprey" When Zach sees that the Wild Kratts have lost their keys in the water, he sends his Zachbots out to search for them so he can steal their technology once again. And to keep the crew from contacting Chris and Martin he casts a communication blocking net, but they soon find out, so Zach orders one of his Zachbots to cut down the tree where the baby osprey "Fluffy Flyer" is.
- In "Bandito the Black-Footed Ferret" After Martin's mishap with Aviva's Stone Digger leads to the discovery of an unknown colony of endangered black footed-ferrets, Zach decides to steal them so he can outfit them with robot parts to steal stuff.
- In "The Amazing Creature Race" Zach is be forced to exercise (doctor's orders) hating running and watching the Wild Kratts on his big screen he sees they're planning a race to see which animal is the best all-round runner. So he builds armor to fit out the animal who's the best who appears to be the pronghorn antelope. He then shows up and steals one Martin named "Pacer" right out from under them, but Chris and Martin spoil his fun by flattening his tires and leading a herd of stampeding bison his way.
- In "Lemur Legs" Zach and Donita are notified by Gourmand telling them that he'll be serving sifaka lemur legs as his main dish.
- In "Praying Mantis" Zach hears the Wild Kratts and Wild Kratt Kids Gavin and Ronan talking about praying mantis' and how they use their raptorial arms to catch prey. So he decides to mechanical create mantis arms of his own which uses to steal the miniaturizer and in addition has 2 of his Zachbots kidnap Koki and Jimmy. He then uses the miniaturizer to enlarge his Zabots to attack Martin (whom has Praying Mantis Powers), then Aviva uses Mantis Powers herself only she's colossal which makes Zach super scared and sends him in his jet flying.
- In the special "Back in Creature Time Parts 1-2" Zach is bragging to his Zachbots about how he claims he's the greatest inventor ever, but he wants more inventions. So he orders his Zachbots to spy on the Wild Kratts while he works on his latest invention "An Invisibility Cloak". When he hears that Aviva has created a time machine he's outraged, claiming that was his idea, that's when he gets the idea to put his invisibility cloak to the test. So he travels to the Philippines and sneaks into the Tortuga undetected, where he surprises Koki, hits the mute button so they communicate with the guys, captures her and Jimmy and travels back in time so he can trap Chris, Martin and Aviva back in time. Once back in time he puts his plan into action, by having one of his Zachbots hide and wait to capture Aviva while he tells Chris and Martin that he's trapping them in time by jumping back to the future and disintegrating their end of the time machine. Fortunately with the help of Tasmanian Tiger Powers they are able to stop Zach and get back home as he flies away on his Zachbot.
- In the holiday special " A Creature Christmas" Zach, Donita, Dabio and Gourmand have teamed up in a holiday plot to steal the Wild Kratts baby animal friends by trapping them in giant Christmas ornaments, hanging from a robot tree in front of a mall owned by Zach called "Varmitech Village". After Chris, Martin and Aviva's plan spit up to stop them backfires so they regroup and head to Varmitech Village where they undecorated the tree setting the animals free. As the villains watch the Wild Kratts play happily with their baby animal friends they are very annoyed, though they expected this so they pretend to be touched by their animal friends and say that they'll do a one time kindness and help them return their animals friends. But when the villains present the Wild Kratts with a present for each of them only for them to find out they've been tricked. So then the villains take all the Wild Kratts stuff, except the Creature Power Discs letting the Wild Kratts keep them to remind them of their defeat. The villains then leave them on a large ice float in the middle of the ocean and return to redecorate their tree. But the villains overlooked Aviva's latest invention which is in Martin's pocket; a keychain button designed to summon his and Chris' power suits whenever they need them. With their suits back, they use their creature powers to get back much to Zach's surprise, realizing that he and his fellow villains have not defeated the Wild Kratts, and the brothers un-decorate the tree yet again. Zach's Zachbots and Donita's mannequinbots try to stop them, but Jimmy activates the Tortuga disrupt-o-blast which stops them. But Zach has one final trick where he activates his robot tree to stop them, but the brothers manage to defeat it. But the villains refuse to be defeated, unfortunately they forget the baby animals have names and the villains are soon trampled by the baby animals in an adorable defeat. As they flee the mall in fear Zach exclaims "Who needs Christmas anyway!"
- In "Animals Who Live To Be 100 Years Old" Zach realizes he's getting old when he sees a wrinkle on his face, when Donita tells him there is no fountain of youth he believes that if anyone can find it it the Wild Kratts. Coincidentally he hears they're looking for animals that live over 100 years old, so he decides to do his own research and stay one step ahead. First he tells them that he's going after a salamander called "The Human Fish", but its really a trick so he can really go after the bowhead whale; who can live to over 200 years old. Once they get there after stopping him, Zach angrily overrides their ship sending them into the Sea of Japan where they find a school of immortal jellyfish who the creature power to live forever. Even Zach thinks by eating them he'll live forever, his plan backfires after he almost eat Chris and Martin.
- In "Panda Power Up!" Zach wants to make robotic stuffed animals out of real live animals and when he sees Aviva's stuffed panda toy land on his ship's windshield he decides to use Pandas as his model. Once in China he soon bumps into the Wild Kratts' Tortuga and sees their engine control panel is open he orders his Zachbots to drain their power. Then he when he finds Chris, Martin and Aviva he steal's Chris' Creature Pod, the Buzz Bike's Power along a mother Panda and Martin (in his panda suit) and leaves Chris and Aviva alone in the wild with no power or communication. Fortunately with help of using bamboo as excess energy, they are able catch up with Zach, release Martin and the others pandas and even retrieve Aviva's stuffed panda toy.
- In "Golden Snub-Nosed Monkey Man" Zach plans to capture the legendary yeti to put on display and charge money for admission. But when he thinks he's found one, he soon discovers that its really Martin in a Golden Snub-Nosed Monkey creature power suit. When Martin tell Zach that he'll tell everyone who he is, Zach threatens to do bodily harm to Martin's monkey friend Blue Goggles. But soon Chris and Aviva show up and defeat Zach and save Martin and Blue Goggles.
- In "Red Panda Rescue" Zach wants to get Donita a weasel stole for her Birthday. So he hacks into the Wild Kratts computer system to see what type of weasels there are and when he sees Chris with a baby red panda he decides that he wants to steal it. So he and his Zachbots break into the Tortuga and steal her right out from under the crew and puts Aviva, Koki and Jimmy Z in a communication blocking net. But before he can get away Chris and Martin arrive and Zach quickly has his Zachbots form a protective circle and hides the red panda cub (whom Martin named Lost and Found) inside one of them. A chase soon begins as Chris and Martin pursue after Zach and his Zachbots, in the end Lost and Found is rescued and Zach is left a present for Donita.
- In "Musk Ox Mania" while going through his "Finders-Keepers" collection Zach realizes he doesn't have anything from the Wild Kratts. So by spying on them he hears that Chris has lost his "Creature Souvenir" collection and how it contains some of the stuff he needs to activate Creature Powers Zach Decides to go to the Arctic and steal it. Once he found it a pack of Arctic wolves showed up thinking Zach was a musk oxen due to his enormous hairy coat, then when he had his Zachbots for a defensive ring around him the lead musk ox also thought he was a musk oxen too and charged at him and his Zachbots destroying them, making Zach give up.
- Despite his schemes revolving around using animals for his own purposes, he is shown to be afraid of them as well.
- As seen in "Skunked!", his favorite food is tomato soup.
- In the episode "Mystery of the Weird Looking Walrus", Aviva claims he has 6 toes on his left foot and that his favorite color is chartreuse.
- Shadow the black jaguar seems to be the only baby animal who likes Zach, possibly because he (Zach) is black like him.
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