Runt is the smallest and most vulnerable of a litter of five wolf pups. Eager to please and desperate to prove his worth, he struggles against his father's assumption that he will not survive the harsh realities of the wild. Because he lacks the physical size and obvious talents of his siblings, he searches constantly for chances to display his bravery and secure a useful place within the pack.

Bider is an older, pure white wolf who joined King's pack after losing a battle and being deposed as the leader of his previous family. He lives up to his name by quietly waiting for an opportunity to exploit any weakness in King's leadership. He uses his influence to manipulate Runt, taking advantage of the young pup's need for validation to turn him against his father.

King is a large black wolf with a white star on his chest, serving as the strong and experienced leader of the pack. He operates under a strict belief that only the strongest survive, leading him to maintain an emotional distance from his smallest son. His leadership style relies heavily on careful risk management and a deep-seated distrust of humans.

Silver is King's mate and the mother of the pack's pups. She possesses a keen intuition for assessing the strengths of her offspring, allowing her to bestow names that reflect their future contributions to the pack. She provides a vital source of comfort for Runt when others dismiss his potential.

The Raven is an unnamed bird who maintains a symbiotic relationship with the wolf pack, helping them locate prey in exchange for scavenging the remains of their kills. The bird acts as an unexpected guide for Runt, questioning the pup's demeaning name and warning him away from dangerous situations.

Thinker is one of Runt's brothers from the new spring litter. Like his other siblings, his name reflects his natural abilities, and he grows quickly alongside them. He accompanies Runt on explorations around the territory, sometimes bearing the consequences of his smaller brother's reckless attempts to prove bravery.

Helper is a yearling wolf, roughly one year older than Runt and his littermates. He takes on responsibilities within the pack, such as babysitting the pups while the older wolves go out to hunt, and teaching Runt essential survival skills like how to stalk silently.

Hunter is a yearling wolf in King's pack, born the year prior to Runt's litter. He participates in the pack's hunts and helps maintain the family's survival alongside his brother Helper and the older adult wolves.

Leader is one of Runt's littermates, named by Silver for the dominant traits he exhibits right from birth. He quickly grows strong on his mother's milk, easily securing his place in the pack hierarchy while his smaller brother struggles for space.

Sniffer is a pup in Runt's litter, named by Silver for his keen sense of smell. He uses his natural gifts to establish his usefulness to the pack as he grows and explores the woods.

Runner is one of Runt's brothers, characterized by his speed and agility. He quickly lives up to his name as he begins exploring the world outside the den, further emphasizing Runt's physical limitations by comparison.

Goldie is a domesticated dog belonging to the humans who live near the woods. She wears a collar and stays tethered to a chain, completely accepting the loss of her freedom in exchange for guaranteed food, shelter, and affection from her human owners.

This unnamed wolf is the leader of a neighboring pack. He intercepts Runt when the pup gets lost during a hunting expedition. Though strict about his territorial boundaries, he shows leniency toward the young and small intruder, pointing him back toward home.