Jeanne is a peasant girl who develops the power of sight and prophecy after experiencing convulsive fits. She is courageous and empathetic, using her visions to assist those who are overlooked by broader society. Relying on the upper classes' tendency to underestimate peasants, she cleverly tricks her pursuers to protect herself and her friends.

William is an oblate at the Monastery Saint-Martin and the illegitimate son of a Crusader and an unknown North African woman. He possesses miraculous physical strength and a deep scholarly intellect. As a biracial youth in medieval France, he frequently faces bigotry and assumes he will be treated as an outsider by those around him.

Jacob is a young Jewish boy with miraculous healing powers. After hateful peasants burn his neighborhood, he sets out for Saint-Denis armed with deep faith and practical medical knowledge. He maintains a rational, pragmatic perspective that frequently contrasts with the credulous behavior of the knights and monks around him.

Michelangelo, often called the Red Monk or Michelangelo de Bologna, is a gigantic, ruddy, and hairy figure. Initially appearing as a terrifying religious zealot hunting down suspected witches in peasant villages, his imposing stature terrifies those he approaches. His true motives slowly come to light as he tracks the magical children across the French countryside.

The Inquisitor is a highly intelligent Papal spy tasked with investigating the supposed miracles of the three children and their dog. Originally seeking to distinguish himself by destroying their "pagan cult," he secretly tracks their movements, observing their powers firsthand while strictly documenting their actions for the church.

Gwenforte is a beautiful white greyhound with a copper-colored nose. Revered locally as a holy beast after returning from the dead, she is deeply bonded to Jeanne and fiercely protects the children. She relies on her sharp animal instincts to judge the moral character of strangers they encounter on their journey.

Known publicly as "Hubert the Good," the Abbot of Saint-Denis is a religious authority who is completely incapable of lying. Driven to extreme paranoia by a terrifying supernatural encounter in his youth, he operates as a dangerous and bloodthirsty zealot.

King Louis of France is a powerful young monarch. Though he casually expresses bigotry toward his Jewish subjects and supports burning their holy texts, he strictly enforces their physical protection and shows genuine awe when interacting with the magical children.

Blanche de Castile is the King's intensely haughty mother. She instantly dislikes the children upon meeting them in the palace corridors, deliberately insulting Jacob and fiercely championing the mass burning of the Talmud.

Sir Fabian is the leader of a ragged group of knights tasked with destroying Gwenforte's grove. Disinherited by his family for killing innocent doctors during the Crusades, he suffers from severe trauma and night terrors that manifest as a high-pitched howling sound while he sleeps.

Marmeluc is one of the crusader knights who helps capture Jeanne and Jacob. Unlike his strictly hostile peers, he shows an open curiosity toward different cultures and engages Jacob in a thoughtful conversation to better understand the tenets of Judaism.

Old Teresa is the wise woman in Jeanne's peasant village. She takes Jeanne under her wing when the girl begins to predict the future, offering guidance and care until the imposing monk Michelangelo suddenly takes her away to face accusations.

Brother Bartholomew is a senior monk at the Monastery Saint-Martin. He delivers bigoted lectures claiming that peasants, women, and non-Christians are in league with the devil, which deeply offends William and sparks a destructive conflict.

Old Jerome is the librarian of the Monastery Saint-Martin. Acting as a storyteller, he recounts William's early years at the monastery, describing the boy's incredible size and the intellectual disputes that lead to his expulsion.

Aron is a large butcher from Jacob's village. After his community is destroyed in a violent raid, his severe burn wounds are miraculously healed by Jacob using yarrow root and prayer.

Yehuda is Jacob's cousin and a highly respected rabbi living in Saint-Denis. He provides a safe haven for the children and patiently explains the rising tensions surrounding the impending destruction of Jewish holy texts in Paris.

Miriam is Yehuda's wife. She offers gentle care and comfort to Jacob, William, and Jeanne, putting the grieving and exhausted children to bed after they arrive in Saint-Denis.

The Companion is an elegant, handsomely dressed man serving in the King's retinue. He acts as a decoy monarch in an abbey garden to protect the real king from strangers, though Jeanne's unique vision easily penetrates the disguise.

Marie is a brewster with close knowledge of Jeanne's early life. Sitting at a tavern table, she shares the history of Gwenforte's resurrection and details Jeanne's first prophetic fits to an eager audience.

The Nun is a mysterious little old woman who contributes significantly to recounting the children's journey. She possesses uncanny knowledge of the children's private thoughts and visions, leading others to suspect she has strange powers of her own.

The Jongleur is a clever, red-headed traveling entertainer. Observing the children and knights at a market town, he embeds himself with their captors by singing bawdy songs in exchange for food and protection.

The Chronicler is a visiting monk from Scotland. He crosses paths with the children at Lord Bertulf's hall and vividly recounts their bizarre, dangerous encounter with a poisonous, flatulent dragon.

Lord Bertulf is a local nobleman who hosts Sir Fabian's knights, the captive children, and a visiting chronicler. He demands that the knights slay a marauding dragon in exchange for an escort to Saint-Denis, setting up Jacob's bizarre confrontation with the beast.