The narrator is a quiet, solitary seven-year-old boy who prefers reading books and listening to classical music over playing with peers. Feeling alienated from his own family, he is unusually perceptive and possesses a deep sense of compassion. He finds comfort and safety at Hempstock Farm after an otherworldly incident brings him to their property.

Lettie is an eleven-year-old girl who lives at the end of the lane and claims to have traveled across her pond as a baby. She is fearless and highly protective. She acts as the narrator's guide to the hidden, magical elements of the world and takes responsibility for keeping him safe.

The eldest resident of Hempstock Farm appears as a thin woman with wispy gray hair. She is highly knowledgeable about the supernatural forces surrounding the property and casually mentions remembering a time before the moon existed. She acts as a powerful, stabilizing presence for her family and their guests.

Ginnie is a stout, practical woman with a ruddy face who helps run Hempstock Farm. She is warm and firmly protective, providing the narrator with comforting meals and a sense of maternal security he lacks at his own home.

Ursula appears as a kind, tall, and pretty young woman hired as a nanny. She is actually an ancient, hostile entity attempting to cross into the human world. She uses her attractive disguise to manipulate adults while secretly terrorizing the young narrator and isolating him from his family.

The hunger birds are shadowy, spectral creatures that exist outside the human world, functioning as cosmic cleaners. They swarm to eliminate magical disturbances or entities that do not belong in the normal universe, operating with a ruthless, insatiable drive.

The narrator's father is a practical man who works in business and wishes his son were more interested in sports than books. He has a history of childhood trauma that affects his parenting. He quickly falls under the manipulative influence of the new nanny, leading him to turn against his son.

The narrator's mother is a busy woman who recently accepted a new job as an optometrist. Because her career keeps her occupied during the day, she hires Ursula to watch over the children. She remains entirely unaware of the nanny's malevolent nature or the danger her son faces.

The narrator's sister frequently argues with him and dislikes his quiet habits. She resents having to share her bedroom with him during financial difficulties. She is easily won over by Ursula's superficial charm, wishing she could be just like the new nanny.

The opal miner is a tall, tanned man who rents a room in the narrator's childhood home. He struggles with severe gambling debts, and his tragic actions early in the story inadvertently trigger the supernatural events that follow.

Ocean is a black kitten with striking blue-green eyes. The narrator finds her while exploring Hempstock Farm's magical grounds and immediately bonds with her, naming her after Lettie's pond. She provides him with silent comfort during his terrifying ordeal.