Kraang was once an Utrom scientist who discovered a mutagen derived from the Kraathatrogon. Using this substance, he mutated to gigantic size and developed powerful psychic abilities. Using his new powers, he conquered and enslaved the majority of his race, destroying their individuality and turning them into mental clones of himself. He renamed himself Kraang Prime and called his faction 'the Kraang'. He then proceeded to conduct a centuries long campaign to conquer Dimension X, and later the greater universe as well.
Kraang Prime first appears in a message he transmits to his race at TCRI. He announces that the full invasion has begun, after which the Kraang announce that the portal is to be prepared to summon the Technodrome. The Turtles find out about this at almost the same time using the stolen Kraang communicator. After the Turtles destroy the portal, they discover that the Technodrome still managed to slip through and he begins his attack. Shortly afterwards they discover that April has been kidnapped by Shredder and given to the Kraang.
April, meanwhile, wakes up from her kidnapping in Kraang Prime's 'throne room' strapped to an apparatus. Kraang Prime introduces himself as 'Kraang' and explains that he required April's uniquely attuned energy signature to stabilize the terraforming process. Now that he has her, the terraforming of Earth begins, with people beginning to choke outside as the air is changed. However as the Technodrome builds energy to wipe out all humans in the area the Turtles arrive and pull April out, while delivering a kick to Kraang Prime.
After the heroes flee, Kraang Prime reveals his exo-suit hidden in the walls of his throne room, and proceeds to pursue the Turtles as the Technodrome malfunctions. He catches up to them in an escape pod launch tube where he tries to kill them. The Turtles and April are saved by Leonardo, who remains in the Technodrome to hold Kraang Prime off while the rest escape. An explosion rocks the flying fortress as the escape pod leaves, and both are thought dead. However Leonardo is shown to have survived shortly after, and the re-activation of the Technodrome on the ocean floor shows that Kraang Prime did as well.
He communicates telepathically with the Kraang in the rebuilt TCRI building. However, he then detects April tuning in on their telepathic conference and sets his minions on alert.
Kraang Prime informs the Technodrome that all Kraang in Dimension X are mobilizing for the invasion of Earth. he then addresses the Kraang in charge of Plan 10, which is to switch human leader minds with Kraang minds, unaware that Raphael had accidentally swapped brains with this Kraang. Despite a poor imitation of Kraang speech, Raphael claimed that Plan 10 was clear to progress, so Kraang Prime gave the order to implement it. However, the rest of the Turtles were able to infiltrate the Technodrome, restore Raphael to his proper body and destroy the neuro-switcher, causing damage to the Technodrome in the process.
Kraang Prime was watching from a view screen as the Kraang had successfully perfected the mutagen for the invasion.
Kraang Prime appeared at the beginning of the episode at Shredder's Lair over a project screen where the Shredder contacted him. He then asks the Shredder like Tiger Claw did moments ago for a decision over their alliance. He then agreed that in exchange for the Kraang to 'deliver' Splinter and the Turtles to the Shredder and reversing Karai's mutation, the Shredder will make sure that the Kraang take over New York and then the world. Raph and Casey are roaming the wrecked streets when, all of the sudden, a massive portal opens up before them, only for Kraang Prime to step out of it, outfitted in a large robotic suit and a ray on its robotic arm from which it can blast Mutagen. Kraang Prime catches up to Casey and Raph and is about to attack them, but the Earth Protection Force comes forward and they surround Kraang Prime, giving Raph and Casey a chance to escape. Kraang Prime later finds them again and shoots Mutagen on to Kirby O'Neil turning him into a Kraang-like monster. Kraang Prime later manages to find the Turtle Mech and engages it in combat. Donnie then launches a barrel of waste at Kraang Prime's face, however the chemicals had no effect on the fearsome Kraang Prime. Kraang Prime then tells the Turtles and April that they have no right to stop the Kraang's invasion of humanity, as Kraang Prime claims that millions of years ago it was he who mutated Earth's early inhabitant (insultingly referring to them as "monkeys") into modern humans using mutagen, and they have now come to Earth to do what they please, seeing it as their right for giving humans intelligence. Regardless of his bantering, the Turtle Mech continues to fight against the strength of Kraang Prime's robotic suit, but the sheer force of the battle damages the Turtle Mech quickly. Donnie decides to use the mech's electric harpoon, even though this may fry the mech. While one end of the harpoon latches on to a transformer and taps into the city's power grid, the other end latches on to Kraang Prime's face and electrocutes him. This causes all of the electricity inNew York City to go out as well as Kraang Prime and his robotic body to collapse. The Turtles and April celebrate, but this is short-lived as Kraang Prime comes out of his suit and runs towards the now useless mech. The Turtles and April all escape on to a sidewalk and April uses her mental powers to attack Kraang Prime just when Casey drives the Party Wagon into the monster, briefly knocking him out. Everyone climbs into the van and drives off. Leaving Kraang Prime and his subjects to control the city.
Kraang Prime revels in the Technodrome being raised alongside Kraang Subprime who finishes repairing it, however moments later it is destroyed by the Triceratons, possibly killing them there.
Kraang's origins were revealed to the Turtles and Fugitoid by the Utrom Council, he originally was a scientist who discovered the mutagen in Kraathatrogon worms which he used to heighten his abilities to the point where he could take over the minds over the majority of Utroms and converting them into the Kraang Hive mind.
Kraang Prime resembles most others of his species, except that he is much larger; over 10 feet in diameter. His pupils are star shaped instead of diamond shaped like the other Kraang and has tendrils over his mouth. He also has three hexagonal decorations on his forehead. His tentacles are bulky and dark red. When needed he can move about in his custom built robotic body. The body is a massive, 25 foot mechanical weapon with long tentacle-like arms and a powerful energy weapon mounted at the head much larger than other Kraang droids.
- "The invasion that is known as the invasion of Earth begins...NOW!"
- "Like all Kraang I am called Kraang, But you can call me Kraang."
- "The Turtles?! Kraang will not be stopped by pathetic mutants!!"
- "Kraang agrees to this, but in return Shredder must then help Kraang conquer the city known as New York City and then…THE WORLD!"
- "Lowly insects, do you think Kraang can be stopped? It was Kraang that found your planet millions of years ago, it was Kraang that used mutagen on the monkeys turning them into lowly humans and it is Kraang who now transforms your world."
- "You will all SUFFER!!!"
- Kraang Prime speaks without the aid of his exo-suit and does so in a much less redundant way than his minions. He even refers to himself in the singular, specifically naming himself 'Kraang'. He does, however, occasionally slip into the redundant habit of his lessers.
- While the bulk of Kraang's exo-suit is radically different to his 1987 counterpart's robot body, the head shares the same antenna as well as purple markings similar Krang's robot body's glasses.
- Kraang Prime is unique in that he is the only mutant in the 2012 series to have been originally of an unearthly species.