Emily is a 12-year-old orphan who moves to New Moon farm to live with her maternal aunts after her father's passing. She is a deeply imaginative, proud, and sensitive girl with a fierce determination to become a professional writer. She experiences intense moments of creative clarity that she calls "the flash" and relies on writing to process her emotions. Raised unconventionally by her father, she frequently questions strict societal rules and authority figures.

Douglas is Emily's beloved father and a former journalist who never achieved financial wealth. Following his wife's death, he raised Emily on his own, choosing to educate her at home and encouraging her wild imagination rather than sending her to a traditional school. He holds expansive, gentle views on religion and nature that sharply contrast with the strict Victorian norms of his late wife's family.

Elizabeth is the stern, traditional elder sister who manages New Moon farm. She operates with a strict moral code and believes heavily in family pride, propriety, and discipline. Though she frequently punishes Emily for her unconventional behavior and views fiction writing as a wicked habit, her harsh exterior hides a genuine, deep-seated love for her deceased sister's child.

Ilse is a passionate, fiery tomboy who lives next door to New Moon farm. Raised by an emotionally distant father, she lacks supervision, attends school sporadically, and frequently questions the existence of God. Despite her explosive temper and tendency to hurl creative insults, she is fiercely loyal and becomes Emily's closest confidante.

Laura is the younger of the two Murray sisters living at New Moon farm. She is gentle, sweet-tempered, and highly indulgent toward Emily, often sneaking her treats or quietly supporting her when Elizabeth is overly harsh. She provides the maternal warmth and comfort that Emily desperately needs while adjusting to her new life.

Jimmy is Emily's cousin who works the land at New Moon farm. The townspeople consider him mentally simple due to a childhood head injury caused by Elizabeth pushing him down a well, but he is actually a deeply observant and poetic soul. He memorizes and recites his own poetry and maintains a beautiful garden that Elizabeth is forbidden from controlling.

Teddy is a pale, delicate boy who joins Emily's small social circle. He possesses an immense natural talent for drawing and sketching, which mirrors Emily's drive for writing. He lives a relatively isolated life due to his mother's overbearing nature but thrives when surrounded by his imaginative friends.

Perry is an ambitious, energetic boy from the impoverished Stovepipe Town neighborhood. After spending his early childhood sailing the world with his late father, he moves to Blair Water and takes a job as a farmhand at New Moon. Highly competitive, he decides to attend school simply because Emily does, quickly rocketing to the top of the class.

Nancy is an aristocratic, elderly relative who lives at the eccentric estate of Wyther Grange. Now in her eighties, she is wealthy, unapologetic, and highly independent. She enjoys gossiping, ignoring tradition, and recounting stories of her youthful beauty to anyone who will listen.

Dean is a 36-year-old intellectual who walks with a stoop due to a sloped shoulder, earning him the nickname "Jarback" among the townspeople. He is highly educated, loves literature, and previously attended school with Emily's father. He becomes a close confidant to Emily, sharing poetry and walking with her, though the significant age gap colors their dynamic.

Mr. Carpenter is an older married man with a dynamic, engaging teaching style. Rumored to have squandered a brilliant future due to a "fast crowd" in his youth, he now dedicates himself to his students. He possesses a sharp eye for true talent and pushes Emily, Teddy, and Perry to refine their respective crafts.

Ellen is the complaining, pessimistic housekeeper who works for Douglas Starr. She disapproves of how Emily is being raised, believing the child needs strict socializing and a harsher religious upbringing. She frequently vocalizes her physical ailments and leaves the household shortly after her employer's death.

Dr. Burnley is the Blair Water physician and a vocal atheist, which causes the religious townspeople to view him as an infidel. He is entirely consumed by his medical practice and deeply held bitterness regarding his wife's disappearance, leading him to severely neglect his daughter's upbringing.

Rhoda is a classmate who initially pretends to befriend Emily by complimenting her beauty and her family's social status. She is highly concerned with class and popularity, quickly dropping Emily when a wealthier, more influential girl demands it.

Miss Brownell is the condescending, tyrannical first teacher Emily encounters in Blair Water. She takes pleasure in humiliating students publicly and shows particular disdain for Emily's poetry, attempting to mock it in front of the entire class.

Lofty John is a Catholic neighbor whose property contains a grove of trees beloved by the children. He holds a grudge against Aunt Elizabeth and uses dark, teasing humor, once convincing Emily that she has eaten a poisoned apple.

Father Cassidy is the good-natured Irish Catholic priest serving the local community. He is charmed by Emily's bold request and actively encourages her writing, showing her a warmth and open-mindedness that contrasts with the strict Protestant views of her family.