Martin William Kratt is a member of the Wild Kratts crew; he is the older Kratt brother, and one of the the main characters of Wild Kratts. Although he is the elder brother, Martin has a more playful side and is characterized by the color blue.
Martin is a young man of average height; he usually wears hiking boots, khaki shorts, and a blue jacket with the zipper zipped almost all the way down and black stripes running across the sides with the sleeves rolled up, along with his Creature Power Suit. He has blue eyes, tan skin, and sandy blond hair, with the cowlick showing. In Polar Bears Don't Dance, while adventuring in the Arctic, he wore a blue jacket, jeans, and boots, along with his Creature Power Suit. He is taller than his younger brother, Chris.
Martin's favorite color is blue.
Like his brother, Martin is playful, childish, comedic, and simply loves creatures. Due to this, he is often seen as the "jokester" of the group, always cracking up a smile. On the other hand, he is impulsive, overly optimistic, and while usually prepared for any situation, he sometimes isn't. He likes to taking risks, and he is easily distracted, sometimes forgetting that he is on a mission. Martin can be impatient, as seen in Bandito: The Black-Footed Ferret, where Aviva told him not to touch the new invention, the Stone Digger, while the others told him to wait until morning, and he uses it anyways. He tries to be a "big brother" and "save" Chris from "danger". Martin loves to get into the mind of creatures, and often ifentifies with them, specifically when in the use of a Creature Power Suit. However, he does know when to be serious, and he makes a good teammate. He also knows when to put a creature adventure aside, as shown in "Fossa Palooza", when the team had to go home for Mother's Day. He dearly loves his fellow creatures, and enjoys giving them names, especially the younger ones.
Martin works with his brother, Chris, and their friends to learn about animals and save them when necessary. He uses his creature knowledge, swimming skills, and creature powers to save the creature world. He has extensive knowledge of various creatures, as he is a professional zoologist. He is an exceptional swimmer; he also knows how to water ski, snowboard, and "manta board".
-Martin and Chris talking about a previous zebra stampede
- Martin and Chris grew up in Warrentownship, New Jersey.
- He plays "extreme-hide-and-seek tag" in Mimic.
- Martin gives Jimmy piggy-back rides in "The Gecko Effect".
- In "To Touch a Hummingbird", Martin sips some of Gourmand's chocolate sauce that was supposedly for some hummingbird eggs. He claimed that chocolate sauce was his favorite sugary liquid.
- Martin has two sons, Ronan and Gavin, although unrelated to Martin in the show.
- Martin is currently 51 years old in real life.
- Martin has been called an "animal lover", "tree hugger", and "a clog" (twice).
- His favorite turtle is the box turtle.
- Apparently, Martin may not be one of the best drivers out there, as seen in "Aardvark Town" when he drove over a ravine. He also did a bit of this off-screen in "Let the Rhinos Roll!".
- It is shown in "Honey Seekers" that Martin is right handed.
- Martin's love of chocolate is a recurring gag.
- In "Tazzy Chris", it is shown that Zach and Martin have known each other since childhood. They are enemies, but their relationship is best described as more of a comedic rivalry.
- Gourmand calls him "Blueberry".
- Zach calls him "Blue Boy".
- Donita refers to him as "Martino".
- Paisley calls him "Mr. Sea Blue".
- Martin called himself "Fish Finder Marty" in "Rocket Jaw: Rescuer Of The Reef"
- Martin is shown to be a good artist in "Honey Seekers", where he drew a realistic lion sketch, and in "Polar Bears Don't Dance", when he made a grand ice sculpture of a walrus and polar bear in battle.
- Martin can play the bongos, guitar and horn.
- Martin doesn't get embarrassed very often, usually only when someone gets after him for misbehaving in some way, like waking someone up, or not obeying due to his impatient nature.
- Martin likes to wake up Jimmy Z by telling him his controller is missing; he first does this in "The Gecko Effect".
- Martin has been shown to get really nervous, especially when miniaturized.
- Martin graduated from Duke University with a Bachelor's degree in Zoology.
- Martin's full name is Martin William Kratt, named so in honor of his grandfather, William Jacob Kratt. 
- Martin claims that he has NEVER worn pink before.
- Martin's favorite arctic animal is the musk ox.
- Martin´s favorite mustelids are martens, mongooses, weasels, ferrets and otters.
- His astrological sign is Capricorn.
- He is the eldest member of the Wild Kratts crew.
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