A highly skilled apprentice magician, adopted by Arthur and Martha, who proves his adeptness at summoning powerful spirits and is determined to seek revenge against those who wrong him.

A rising magician within the British government, who becomes the antagonist due to his ambitious plans involving powerful spirits, even as he seeks to recruit Nathaniel for his abilities.

A middle-ranking magician tasked with mentoring Nathaniel, he struggles to connect with his apprentice and often displays a cantankerous and critical nature.

Nathaniel’s primary caregiver, she forms a close bond with him and exhibits the domestic ideals of a dutiful wife, though she struggles to defend Nathaniel against Arthur's judgments.

Bound spirits working for Simon, these two djinn antagonize Nathaniel and Bartimaeus, with Faquarl showing a powerful presence, while Jabor exhibits transformation abilities similar to other spirits.

A foliot spirit loyal to his summoner, Sholto Pinn, acts as a foil to Bartimaeus, whose disdain for Simpkin's willingness to assist their captors is evident.

Nathaniel's art teacher who challenges his perceptions of magicians’ grandeur and shows concern for Nathaniel’s well-being, standing up for him when he’s threatened.