Big Chill

Big Chill is a Necrofriggian alien from the planet Kylmyys.

Ben first transforms into Big Chill during the episode Kevin's Big Score, to chase down Kevin after he stole the Rustbucket. Big Chill has an Ultimate Form.

Appearance
A moth-like alien, Big Chill has an eerie blue skin and green eyes. Big Chill's wings and antennae can fold up into a cloak of sorts, giving him the appearance of a phantom. He can become intangible, fly, and breath ice.He can also freeze the objects he passes through when he is intangible.

Abilities/Weakness
A moth-like alien, Big Chill's wings and antennae can fold up into a cloak of sorts, giving him the appearance of a phantom. He can become intangible, fly, has superhuman strength despite his frail appearance, and can breathe freezing vapor. He can also freeze the objects it phases through at his discretion. Counter-intuitively, Big Chill is easily capable of withstanding extreme heat, at one point drinking molten metal directly from a massive smelting cauldron. He can also make ice beams from his hands. It is also shown he can control the flows of his ice beams in Above and Beyond, when he is facing off with Alan. In Map of Infinity, his species is shown to be able to spit ice crystals, and in Deep, he is shown to be able to breathe underwater.

Ben 10 Jr. - Ultimate alien
It appears in Ben Jr. 10 - Ultimate Alien as the favorite alien of Ben Jr. and Ben 10000

Ben 10: Star Command Files
And some other episodes.
 * Entrance to Torque
 * Poisonous
 * The Return of the Revenge of the Swarm (goes ultimate)