Kendra is a cautious thirteen-year-old girl entering high school. Naturally intelligent and methodical, she prefers to follow rules and avoids mischief. When she realizes the property hides magical secrets, she initially tries to avoid danger but slowly steps out of her comfort zone to protect her family.

Seth is an energetic eleven-year-old boy who views the trip to Connecticut as an opportunity for exploration. He actively ignores warnings and seeks out hidden monsters in the surrounding woods. His curiosity consistently pulls him into risky situations, forcing him to learn the tangible consequences of breaking the rules.

Stan Sorenson is the stern caretaker of Fablehaven who hosts his grandchildren while their parents take a cruise. He initially lies about the dangers of the woods, citing ticks and Lyme disease, to keep the children safe from magical creatures. He deeply respects the treaties that govern the preserve and demands strict obedience to maintain order.

Ruth Sorenson is the maternal grandmother of Kendra and Seth. She is a resilient and practical woman with extensive knowledge of the magical weapons and artifacts hidden around the property. She treats the children as equals, offering them direct truths about the dangerous entities surrounding them.

Muriel Taggert is a mortal woman who meddled in dark magic and became a witch. She is confined to a shack in the woods, gnawing on a knotted rope that limits her power. She appears physically grotesque with matted hair and missing teeth, yet she speaks with an incredibly smooth, melodious voice to tempt visitors inside.

Bahumat is an ancient demon who terrorized the land before being imprisoned by early European settlers. He represents a profound source of dark magic and chaos, resting beneath the Forgotten Chapel while dark forces work to release him.

Lena is the aging but graceful housekeeper at Fablehaven who retains an exotic beauty and hints of Asian ancestry. She carries unusual habits, such as happily gardening during rainstorms. She offers an entirely different perspective on life and aging, carrying memories of a past existence that differs vastly from mortal humans.

Dale is the reserved groundskeeper of the Fablehaven estate. He is frequently seen leaving out pans of milk and handling the outdoor chores while carefully avoiding the children's direct questions. He takes his duties seriously and acts as a quiet protector during dangerous events on the property.

Maddox is a traveling fairy salesman who visits the estate to conduct a business deal. He is highly knowledgeable about various magical preserves and brings news of outside threats. He stores his fairies in small containers, an act that deeply influences the younger residents of the house.

Hugo is a massive golem constructed entirely of earth. He serves as a powerful laborer on the farm, handling the heaviest and most physically demanding chores. He completely lacks his own free will, acting only on the orders he receives from the caretakers.

Viola is a gigantic magical cow hidden away in a massive barn on the property. Her milk possesses magical properties that allow mortals to see the true nature of the creatures inhabiting the preserve. She suffers from extreme discomfort due to her confined living space.

Nero is a greedy and dangerous cliff troll who possesses a valuable seeing stone. He lives in a cave accessible only by climbing a series of wooden poles. He refuses traditional treasure, preferring to negotiate unique bargains in exchange for his services.

Mendigo is a wooden limberjack marionette kept by the witch in the woods. He is brought to life through dark magic and serves as a completely mindless minion, ruthlessly carrying out physical attacks without any personal agency or intention.

The Fairy Queen is a powerful magical entity whose presence is represented by a small weeping statue. Her shrine rests on a tiny island in the center of a hidden pond. She only offers her assistance to those who approach her with pure intentions and a lack of mischievous deeds.