The Formlings are a group of Ninjago: Masters of Spinjitzu minifigures.
The Formlings are a tribe of shapeshifters from the Never-Realm, where they long enjoyed a peaceful existence. Each member of the tribe had the potential to unlock a single animal form into which they could transform. These forms included bears, birds, deer or caribou, and wolves. Each member of the tribe received a headress denoting their animal form.
At a certain age, children of the tribe would undergo "the Choosing", a rite in which they would unlock their animal forms. However, one of their number, Vex, failed to gain a transformation, and became known as "the Formless." Embittered against his people, Vex left them and spent an unknown period plotting revenge against them. On the eve of the Choosing for Akita and her brother Kataru, Vex returned having allied himself with the Ice Emperor.
He offered them the chance to submit to him, but the Formlings refused, and Vex departed swearing vengeance. Akita and Kataru later returned from their Choosing to find the entire village encased in dark ice, courtesy of the Emperor's Ice Dragon. The two siblings became separated, each believing the other to be lost. Years later, the Formlings and the Ice Emperor's other victims were freed, and Vex was cast out once again.
Kataru (voiced by Cole Howard) is the twin brother of Akita.
Kataru and his sister both embarked on their Choosing at the same time, despite an unsettling visit from Vex. Kataru was quick to comfort his sister, who feared that she, like Vex, might not gain an animal form. Fortunatley, both siblings gained transformations, with Kataru gaining the power to become a bear. Sadly, they returned to their village to find it encased in ice, and were then attacked by the Ice Emperor's dragon, Borea.
Losing sight of Akita in the fight, Kataru thought her lost with their people, and was himself made a prisoner in the Ice Castle. Bound with dark ice chains that prevented him from transforming, he attempted for a time to keep track of the days he had spent imprisoned, but ultimately gave up the effort. He would be visited and mocked at times by Vex, who attempted to persuade him to join the Ice Emperor's Blizzard Samurai. Kataru refused, but grew increasingly despondent until Lloyd, the Green Ninja, was imprisoned in the cell beside him.
Grimfax, Vex's unwilling lieutenant, freed the pair from their cells in hopes of overthrowing Vex and the Emperor, and led them to destroy Vex's dark ice viewing shard. They were intercepted by Vex and a number of guards, and Kataru joined Grimfax in battling them while Lloyd went after the Emperor. The two were ultimately subdued, but when the Emperor regained his personality as the ninja Zane he freed all the Blizzard Samurai from his control. Kataru was then reunited with his sister Akita, and then they rejoined their freed people. After the Ninja departed for their home realm, Kataru expressed the belief that Akita would not see Lloyd again, but she was more hopeful.
The Formlings' Leader (voiced by Brian Drummond) was a tall, bearded man with an eagle headdress presumably denoting his transformation. He presided over the start of Akita and Kataru's Choosing, which was disrupted by the arrival of Vex. When Vex accused the others of casting him out, the Leader declared firmly that Vex's exile was of his own making. Vex offered the Formlings the chance to submit to him, but the Leader demanded that he depart; Vex did so, warning that he had found power that would dwarf their own. The Leader was frozen along with the rest of the Formlings when the Ice Emperor attacked their village.