- "They're kinda cute, if you have a thing for polar bears."
- -Stella to Balto
Muk and Luk, two polar bears who usually like to play pranks on Boris. They are presumably brothers. Most about Muk and Luk's origin is unknown. Muk and Luk live in the forests of Alaska. They are often seen visiting Boris and Balto.
Muk and Luk resemble the Polar Bears indigenous to the Arctic Circle. Muk has a solid black nose while Luk's is red and both have thick white fur coats.
Muk is the smaller of the two while Luk maintains a large physical, yet glutton size.
Both Muk and Luk show very peculiar personalities and traits for their own species. Both are fun loving and carefree.
Seemingly the only thing they take serious in their lives is the well being of their friends in family. Particularly their "Uncle" Boris and Balto.
Muk has shown to be the more intelligent of the two, but Luk also contributes muffled words of wisdom on the given occasion.
Unlike the average Polar Bears, Muk and Luk show no solid traits that usually pertain to the largest bears in America.
They always seem to find the best in every situation, no matter how grim it might be.
Very little is told about the past lives of Muk and Luk before the events in Balto.
During the film both are known to the goose Boris and wolfdog Balto. They seem to have been separated from their family at a young age and were taken in by a probably reluctant Boris.
They now refer to him as their Uncle and only remaining family. During the events of Wolf Quest, they continue to share a strong familial bond with Boris. Later on during Wings of Change, they continue to reside in the wilderness around Nome. They also aid Balto in his quest to rescue the stranded pilot Duke from the Alaskan Wilderness, telling him the exact location of his downed bush plane. After aiding Balto in a confrontation with two wild Bull Moose, they return to a life of little cares and pestering of their Uncle and closest friends.