Jack is an eight-year-old boy living in Frog Creek, Pennsylvania. Methodical and cautious, he carries a red backpack to hold his notebook, pencil, and reference books. He relies on logic and reading to understand the world, making him skeptical of supernatural phenomena. Despite his fear of the unknown, his strong desire to learn pushes him to explore new places.

Annie is Jack's seven-year-old sister. She is daring, highly curious, and favors experiential learning over reading reference books. Her belief in magic and fearless attitude help her accept the strange situations they encounter in the tree house. She often takes the lead during their adventures and encourages her brother to face his fears.

Queen Hutepi is the spirit of an ancient Egyptian royal who resides within a desert pyramid. She is near-sighted and waits patiently for someone to help her read a secret message left in her burial chamber. Her kind and gentle demeanor puts the children at ease despite her spectral nature.

Morgan Le Fay is the enchantress who created the magic tree house. Known initially to the children only as the mysterious "M" person, she fills the tree house with reference books that transport them through time. She leaves small clues, such as a gold medallion and a leather bookmark marked with an "M," which spark the children's curiosity about her identity.

Jack and Annie's mother lives with them in Frog Creek, Pennsylvania. She establishes the boundaries of their everyday routine by calling them home from the woods for meals.

An ancient Egyptian royal and the brother of Queen Hutepi. He hid his sister's copy of the Book of the Dead to protect it from tomb raiders. He also left a secret message in hieroglyphics to help her locate it when the time was right.