Sixteen-year-old Stargirl is a homeschooled, free-spirited teenager who recently relocated to Pennsylvania. Having lost her joyful confidence following a painful breakup, she spends much of her time meditating on the "Enchanted Hill" and adjusting to her new surroundings. Despite her internal sorrow, she remains open-hearted and deeply connected to nature, seeking to spread light in her new community.

Leo is Stargirl's ex-boyfriend from Mica, Arizona. Though he never physically appears early in the narrative, his presence heavily influences Stargirl's daily thoughts and actions. He previously found Stargirl's eccentricities intimidating. He ultimately chose the approval of his peers over their relationship.

Dootsie is a stubborn and deeply curious five-year-old girl who proudly declares herself a "human bean." She frequently sets off on independent adventures and loves attention, sometimes pretending to be invisible when she feels ignored. Her spontaneous, giving nature helps draw Stargirl out of her depression.

Perry is a charismatic, blue-eyed local boy with a cynical attitude and a bad-boy reputation. Nicknamed "Dandy," he is rumored to have spent time in a juvenile boot camp and is known for minor thievery around town. He maintains a harem of devoted girls but catches Stargirl's attention through his rebellious behavior.

Alvina is an angry eleven-year-old tomboy who aggressively pushes away those around her. Known for getting into fights and loudly professing her hatred for boys, she masks a softer interior beneath her tough exterior. She is on the verge of transitioning to adolescence, a change symbolized by a single sparkly pink fingernail.

Betty Lou is a cheerful but deeply isolated woman suffering from agoraphobia. Having not left her house in nine years, she spends her days indoors wearing a purple bathrobe and red slipper socks. Despite her personal fears, she provides a listening ear and wise counsel to Stargirl.

Charlie is a 74-year-old widower who spends every day sitting by his deceased wife's gravestone. Large and beefy in a red and gold plaid scarf, he is deaf but removes his hearing aid at the cemetery to feel closer to his late wife. He is deeply entrenched in his memories of the past.

Arnold is a bulky, solitary man who walks around town in a tasseled green hat. He constantly asks people if they are looking for him without ever waiting for a response. Local children often poke him and run away, treating him as a local oddity.

Margie is the talkative, bleached-blonde owner of the local donut shop. She pushes the limits of pastry cuisine with creations like donut soup, and she serves as a central hub of town gossip and community connection.

Archie is an elderly, retired paleontologist and Stargirl's former homeschool teacher in Arizona. He serves as a wise, grandfatherly figure who understands Stargirl's unique nature better than most, providing her with philosophical advice and guidance from afar.

Stargirl's father is a former engineering supervisor who now works as a milkman in Pennsylvania. He is unconditionally supportive of his daughter, offering gentle guidance and allowing her the freedom to express her unique personality while worrying about her emotional well-being.

Stargirl's mother works as a costumer. Like her husband, she is deeply loving and provides a safe, supportive environment for Stargirl. She largely adopts a hands-off parenting style that encourages Stargirl's eccentricities.

Cinnamon is Stargirl's beloved pet rat. Having moved with her from Arizona, the small animal is a comforting connection to her past and a constant companion during her lonely meditations.

Grace is Charlie's late wife. Though she passed away prior to the novel's events, she is the sole focus of her husband's daily cemetery vigils. Her memory represents enduring, faithful love.

Stephanie is a red-headed high school girl who belongs to Perry's "harem" of affectionate followers. She openly shares Perry's attention with other girls and sports a honeybee tattoo on her ankle.

Thomas is Alvina's younger brother. He frequently clashes with his sister, successfully provoking her rage, such as when he chops off her solitary sparkly pink fingernail.

Neva is a shy, heavily pregnant woman in the community. Seeking to support herself, she takes a job working at Margie's donut shop after Alvina is fired.

Rita is Arnold's mother. She cares for her wandering, solitary son and helps him interact with the broader community when necessary.

Ike owns the local bike and mower repair shop. He is a business owner whose property features prominently in the neighborhood where Stargirl encounters Perry.

Dori is a former classmate of Stargirl's from Arizona. She was the one friend who did not reject Stargirl when the rest of the high school turned against her.

Ponytail is a local girl who is part of Perry's "Honeybees" harem. She wears a honeybee ankle tattoo and shares Perry's affection with the other girls without jealousy.

Zombie is another member of Perry's "Honeybees" group. She dresses in a zombie costume for the town's Blobfest and openly kisses Perry, demonstrating the casual nature of his harem.