Margaret “Meg” Murry is an awkward, mathematics-gifted middle schooler who suffers from low self-esteem and self-loathing. Wearing braces and glasses, she views herself as an oddball and acts out at school, largely due to anxiety over her missing father. She feels a fierce protective responsibility toward her youngest brother and longs for her family to be whole again.

Charles Wallace is Meg's youngest brother, a boy with extraordinary intellectual and telepathic abilities that develop much faster than a typical human's. He speaks in complete, adult-like sentences but only talks to his family to hide his gifts from the outside world. His profound intelligence is matched by a dangerous childhood arrogance regarding his own mental strength.

Calvin is an older student at Meg's school who feels out of place within his own large, neglectful family. Describing himself as a biological anomaly or "sport," he excels at communication and fits in perfectly with the eccentric Murry family. He maintains a positive attitude and eagerly joins the quest into the unknown.

Mrs. Whatsit is an ancient, celestial being who initially appears to the children as a strange, eccentric old woman. Once a star that sacrificed herself to fight the universal darkness, she now serves as a guide for the children's journey. She is exceptionally compassionate and takes a special, comforting interest in Meg.

Mrs. Who is an ancient, powerful being of light who frequently struggles to verbalize her own thoughts. To communicate effectively, she relies on quoting literature, philosophy, and religious texts from across the universe. She specifically aligns herself with Calvin and provides crucial magical tools for the children's journey.

Mrs. Which is the oldest and most powerful of the three celestial guides, finding it difficult to fully materialize into a physical form. She often appears simply as a shimmer of light and speaks with an echoing, authoritative resonance. She operates primarily on logic rather than emotion and takes charge of the group's cosmic travel.

Mr. Murry is Meg and Charles Wallace's missing father, a brilliant government scientist whose experiments with faster-than-light travel went awry. He accidentally trapped himself on Camazotz without fully understanding the forces he was meddling with. While his children view him as an infallible savior, he is ultimately a flawed human struggling against cosmic forces beyond his comprehension.

It is the malevolent, disembodied brain that governs the planet Camazotz and acts as an extension of the cosmic darkness. Operating entirely on hatred, fear, and forced conformity, It controls the minds of the planet's citizens by forcing them to live in synchronized rhythm. It despises individuality and demands absolute submission from all who cross its path.

Mrs. Murry is a beautiful, brilliant scientist who conducts biological experiments in her home laboratory. She maintains a calm, composed exterior that masks the deep sorrow she feels over her husband's unexplained disappearance. Her apparent perfection serves as a constant point of comparison for her insecure daughter, Meg.

Aunt Beast is a towering, eyeless creature with tentacles for fingers who inhabits the planet Ixchel. Because she cannot see, she perceives the universe through an advanced, transcendent understanding of essence rather than visual appearance. She is profoundly nurturing and provides life-saving care to travelers damaged by the darkness.

The Man With Red Eyes is a terrifying lieutenant, acting as a mouthpiece for the malevolent brain that governs the planet. He wears a pulsing, throbbing light atop his head and speaks directly into the minds of his visitors. He represents the dystopian elite of Camazotz, enforcing compliance and warning the children not to resist his control.

The Happy Medium is a jolly, cheerful woman who possesses a magical crystal ball capable of showing events across the universe. She deeply prefers to look at joyful things and is reluctant to show the children the darkness creeping over Earth. She embodies universal joy and provides the travelers with crucial perspective on their cosmic battle.

Mr. Jenkins is the pragmatic and somewhat unsympathetic principal of Meg's school. He questions Meg about her father's prolonged absence, attempting to force her to face the reality of her family's situation. His realistic, blunt approach to the Murry family's problems deeply angers Meg.

Sandy and Dennys are Meg and Charles Wallace's normal, well-adjusted twin brothers. They serve as a sharp contrast to the rest of the eccentric Murry family, blending easily into regular society and participating in typical childhood activities. They encourage Meg to find emotional balance in her volatile life.