Whittington is a rough-and-tumble tomcat with a rumpled, metal-colored coat, thick whiskers, and a drooping left ear. Having been locked out of his former home when his boy was sent to a special school for dyslexia, he carries grief but still desires companionship. He takes pride in his name and claims descent from the legendary Dick Whittington's cat, acting as the resident storyteller for the barn animals and Bernie's grandchildren.

Ben is an elementary-school-aged boy who lives with his grandparents following the death of his mother. He struggles significantly with dyslexia, causing letters to appear reversed on the page and leading to intense frustration with reading. He fears the social humiliation of being placed in special education classes but finds comfort and motivation in the barn animals and Whittington's stories.

Dick is a historical and folkloric figure who loses his parents to the plague and is raised by his grandmother in the late 1300s. Driven by rumors of streets paved with gold, he travels to London to seek his fortune. His ambition, self-driven nature, and lack of self-pity help him establish himself in the merchant trade.

The Lady is a Muscovy duck and the unanimously accepted leader of the barn animals. Her assertive, orderly, and matronly nature gives her uncontested authority over the varied species living together. She enforces the law of the barn, orchestrates truces, and fiercely protects those she views as her found family.

Bernie is the owner of the farm and the grandfather of Abby and Ben. He has a gruff exterior but shows deep compassion for animals, rarely turning away any creature in need of a home. He and his wife foster their grandchildren following their daughter's death, providing a stable, caring environment for the children to process their grief.

Abby is Ben's sister, a school-aged girl who looks older than her years due to the maturity she developed after their mother's death. She takes an active role in helping Ben practice his reading, organizing his lessons in the barn and holding him to high standards. She acts as a supportive anchor for her brother while he works through his academic difficulties.

The Old One is the one-eyed leader of the rats who live in Bernie's barn. He is initially alienated from the larger barn community, as his rats frequently steal food and threaten the chickens' nests. Despite his suspicious nature, he becomes captivated by Whittington's stories, opening the door for a tentative truce with the other animals.

Marion is Bernie's wife and the grandmother of Abby and Ben. She takes an active, sensitive role in supporting her grandchildren through their personal grief and academic struggles. She employs a mentorship style of firm but compassionate guidance, giving the children both comfort and necessary pushes to succeed.

Fitzwarren is a London cloth merchant who also trades in spices and herbs. He takes Dick into his household after the boy arrives in the city with nothing. Recognizing Dick's stoic spirit and ability to identify herbs in the garden, Fitzwarren offers him a position in his business and funds his early trade missions.

Will Price is a coachman who transports Dick to London. He bonds with the young boy during the journey, attempting to warn him about the harsh realities of city life. He acts as an older brother figure to Dick and stays in touch as Dick begins to build his fortune.

Sir Louis Green is a gentleman and the owner of the trade ship the Unicorn. He acts as a benefactor to Dick, offering cryptic but essential counsel about investing wealth into public works like education and clean water. He pushes Dick to read Marco Polo to prepare him for global trade ventures.

Mary is Sir Louis's beautiful granddaughter who frequently dresses in black. She catches Dick's attention and briefly distracts him from his trade duties, though she initially rejects his advances as she is promised to a suitor of high rank.

Miss O'Brian is a Reading Recovery coach at Ben's school. She helps Ben manage his intense frustration with his dyslexia and works with him to improve his reading skills over the summer, treating his struggles with patience and confidence.

Havey is Bernie's dog. He initially enjoys tormenting the barn animals, particularly the Lady, until Whittington stands up to him in a fight. After this confrontation, Havey respects the barn animals' boundaries and peacefully coexists with them.

Coraggio is a brave rooster who lives in the barn. He forms a quick bond with Blackie, an abandoned hen, and survives a frightening attack from a neighborhood dog, maintaining his presence in the barn despite a broken voice following the incident.

Gent is a male duck who visits Bernie's barn during the warmer months. He forms a temporary family with the Lady before his migratory instincts drive him to fly away with the rest of the wild ducks for the winter.