Eleanor is a 32-year-old woman who has spent the last 11 years caring for her abusive, chronically ill mother. Following her mother's death, she lives in her sister's nursery, desperate for a sense of independence and belonging. She joins Dr. Montague's study at Hill House seeking an escape from her stifling family life, taking the family car to make the journey. At the house, she exhibits a highly active imagination and a deep sensitivity to her environment.

Dr. Montague is an anthropologist whose true passion lies in the study of supernatural manifestations. He rents Hill House for three months at great personal expense to write a definitive academic work on psychic disturbances, hoping to gain respect from his colleagues. He acts as a careful host to the younger guests, lecturing them on the house's history and the psychological nature of fear.

Theodora is a free-spirited artist possessing some psychic powers, living a life focused on delight and soft colors. Unlike Eleanor, she is highly confident, unfettered by duty, and quickly makes herself at home. She forms an immediate, sisterly bond with Eleanor that oscillates quickly between warm affection and sharp teasing.

Luke is the roguish nephew of the current owner of Hill House, sent to participate in Dr. Montague's study as a family representative. Known by his aunt as a liar and a thief—mostly of petty cash—he uses frequent humor to deflect the house's oppressive atmosphere. He admits to feeling selfish and lacking a guiding mother figure in his life.

Mrs. Dudley is the passionless caretaker of Hill House who manages the cooking and cleaning. She adheres to a rigid schedule, refusing to stay on the property after dark or deviate from her set times for clearing dishes. She repeatedly emphasizes that no one will hear the guests if they need help in the night.

Mrs. Montague is Dr. Montague's critical wife who arrives to conduct her own paranormal investigations. Unlike her scholarly husband, she relies on superstitious methods like the planchette to communicate with spirits. She openly dismisses the actual phenomena experienced by the original guests while demanding the most haunted room for herself.

Arthur is a grizzly school headmaster who acts as Mrs. Montague's driver and companion for her investigation. He serves as an imposing, hyper-masculine presence who enthusiastically agrees to patrol the dark house with a revolver.

Hugh Crain is the original builder and owner of Hill House. A sad and bitter man who lost three wives on the property, he designed the house's architecture so that every angle is slightly off-center. He wielded oppressive power over his daughters, creating a disturbing, blood-signed book of warnings about sin for one of them.

Dudley is the cranky, abrasive caretaker of the Hill House grounds who guards the locked entrance. He reluctantly allows visitors inside, issuing grim warnings about what they are asking for by entering the property.

Eleanor's recently deceased mother, whose chronic illness required years of dedicated care. Her demanding and abusive nature continues to oppress Eleanor's mind, making Eleanor fear her disapproval even after her death.

Eleanor's domineering sister, with whom Eleanor lives after their mother's death. She attempts to dictate Eleanor's actions and fiercely objects to Eleanor taking their shared family car for the trip.

Eleanor's brother-in-law, who aligns with his wife in attempting to prevent Eleanor from taking the car. He represents another layer of the suffocating family dynamic Eleanor seeks to escape.

Sophia is the younger daughter of Hugh Crain. She was the recipient of a terrifying book created by her father, filled with horrific images of sin and damnation designed to maintain her virtue.