Peter is a ten-year-old blind orphan who survives on the streets of a dodgy port town. Forced to work for an abusive caretaker, he uses his blindness and acutely developed remaining senses to become the greatest thief and lock-pick in town. His bleak life changes when he steals a mysterious box of magical eyes that transports him to a hidden island, setting him on a heroic quest to save the Vanished Kingdom.

Sir Tode is a knight who fell victim to a hag's curse, transforming him into an odd amalgamation of a human, a horse, and a kitten. He originally became a knight by complete accident after a dragon choked on one of his sheep. Seeking a cure for his curse, he joins Peter on his quest, often overcompensating for his small stature and internal fears with exaggerated tales of bravery.

Princess Peg is a fierce, resourceful girl who leads the Missing Ones, a group of children hiding from the king in the palace sewers. She is the author of the mysterious rhyme placed in a bottle to call for a heroic thief. Having survived for years in the fetid underground tunnels, she commands respect through her royal lineage and natural leadership skills.

King Incarnadine is the vicious and paranoid ruler of the Vanished Kingdom. He maintains an iron grip on his subjects by feeding them a mind-altering root called Devil's Dram and terrorizing them with his Night Patrol of giant apes. He forces the kingdom's children to labor in subterranean mines to power his massive clockwork beast, plotting to eventually conquer other realms.

Simon is a battle-scarred raven who serves as a protector and advisor to Princess Peg. Carrying deep physical and psychological wounds from past battles, he constantly worries about his worth as a soldier. Despite his diminished confidence, he is highly lethal, intelligent, and fiercely devoted to the safety of the children hiding beneath the palace.

Professor Cake is the eccentric owner of a magical island situated at the edge of the world. He uses a magical gazing mat to monitor distant waterways and collects cries for help that wash into his Troublesome Lake. Recognizing Peter's unique potential, he gifts the boy a set of Fantastic Eyes to aid him on his quest.

Mr. Pound is Professor Cake's apprentice and agent in the field. He intentionally tests Peter's thieving abilities by leaving a carriage covered in tempered steel locks unattended. By orchestrating this heist, he ensures Peter acquires the magical box of eyes necessary to begin his adventure.

Mr. Seamus is a cruel "beggarmonger" who forces orphans to work the streets. Upon realizing Peter's extraordinary potential, he sells off his other children and locks Peter in a basement, training him exclusively to be a master burglar. He frequently subjects Peter to verbal and physical abuse if the stolen goods are insufficient.

Old Scabbs is an elderly thief who has been banished to the ship-littered wasteland known as the Just Deserts. He bears a "T" branded onto his hand. After being caught trying to steal a lemon from Peter, he agrees to guide Peter and Sir Tode through the perilous desert terrain.

Mrs. Molasses is a resident of the Perfect Palace who takes an injured Peter into her immaculate home. Like all the adults in the kingdom, she is obedient to the king, terrified of breaking curfew, and seemingly oblivious to the dark reality of her society. Her heavily perfumed presence masks the unsettling nature of her compliance.

Frederick is an enormous dogfish, described as being the size of three or four elephants. He approaches the Scop in the uncharted waters, seeking help. After Peter removes the painful hook, Frederick swears to repay the favor.

Captain Amos leads an organized military unit of ravens that guards the Just Deserts. He enforces the strict rules of the wasteland with lethal efficiency. He speaks in cryptic warnings about justice and a "True King," suggesting complex allegiances beyond simple villainy.

Scrape is one of the Missing Ones, a group of renegade children surviving in the sewers beneath the Perfect Palace. Highly suspicious and aggressive toward outsiders, he is quick to resort to violence to protect his fellow orphans.

Trouble, who is also known as Timothy, is one of the young children enslaved by the king who eventually escapes to the underground tunnels. He survives alongside the other Missing Ones under Princess Peg's leadership.

Officer Trolley is a large, thuggish guard equipped with two wooden legs. He monitors the borders of the Just Deserts, enforcing the king's strict ban on magic and aggressively branding the prisoners banished to the wasteland.

Pickle is a small sparrow kept shackled in the Perfect Palace so she cannot fly for help. After Peter frees her and her sisters, she provides him with crucial information about the king's tyrannical methods, the Devil's Dram, and the monstrous Night Patrol.

Longclaw is a massive, horned ape who serves as a high-ranking member of the king's dreaded Night Patrol. He acts as muscle and a personal guard for King Incarnadine, enforcing brutal discipline in the underground mines.