Niju is the main antagonist in Balto II: Wolf Quest. He is a vicious wolf who wants to take over as a leader of the pack.
He was voiced by Mark Hamill, who is best known for his role as Luke Skywalker in the Star Wars Saga, and for voicing the Joker from Batman: The Animated Series.
Niju plans to take over the wolf pack with the aid of his followers, Nuk, Yak, and Sumac. Eventually the wolf pack started to turn towards Niju and started to follow him, but when the ice bridge that led to the caribou formed, the entire pack including Nuk, Yak, and Sumac turned back to Nava, Balto, Aleu. Niju also attempts to kill the pack leader Nava as well as Aleu, but his plans were foiled by Balto. When Niju was given the opportunity to lead the pack, his "fear of change" got the better of him and he fled into the forest. Nava claims to Balto after they were off the ice that he would go and find Niju and that "one would not be whole without the other".
Unlike the elderly leader, Nava, Niju is a very militant, zealous, arrogant, and persuasive wolf who is fully willing to break the rules of the land and steal for what he desired, though seemingly doing so because of the desire to live. He is also shown to suffer from a fear of change (cainotophobia) which probably caused his cruel actions as Nava claimed that Niju would willingly starve or die than leave his homeland. Though he acts as the antagonist of the film, he is not considered evil by fans since Niju was influenced by fear rather than greed, which Steele was driven by in the first film. Many fans also think that Niju may have suffered a traumatic life which led to his fear.
Niju is impressively built, being the second largest (Nuk being larger due to his massive appetite) and almost certainly being the strongest member of the wolf pack which allowed him to intimidate and defeat other wolves, easily tackling and overpowering Aleu and throwing off Nava. His fur is brown with a gray underbelly. His only markings are dark patches around his eyes. In the film, his whiskers were purposely made more noticeable. He also had large paws with his claws always bared and never retracted, showing his vicious nature.