A German American girl seen traveling aboard The Liberty in The Hidden Gold. After her father died at Monsieur LaPlante's hotel, Willamina was sent to New Madrid, Missouri to live with her grandmother.
Marie-Grace's teacher at St. Teresa's Academy.
A customer of Jean-Claude Rey's. Cécile sees him with his son when she and Marie-Grace are sneaking into each other's balls, and she worries that he will spot her.
A young boy who is among the many orphans living at Holy Trinity. He becomes attached to Marie-Grace and enjoys playing with her.
Pierre (The Cameo Necklace)
A circus employee who works with elephants.
He is only seen in The Cameo Necklace.
An abandoned baby left at the Gardners' doorstep in Marie-Grace and the Orphans. Marie-Grace named him for the street he was found on, St. Philip Street. He has blue eyes and brown hair, and his skin is light enough that they cannot determine if he is a person of color. Mr. Hearst, a manager of a local plantation, claims that he is the child of a runaway slave and therefore is the legal property of the plantation. The Gardners care for him until he can join Holy Trinity's orphanage. Cécile and Marie-Grace dress him in fancy clothes so he will be accepted. Marie-Grace also finds comfort in caring for Philip because he reminds her of her brother Daniel, who died four years previously.
Philip is later sent away to an orphanage in Chicago due to the yellow fever epidemic in New Orleans.
An elderly man who works as a butcher, nicknamed the Old Goat Man due to his white hair and beard and resemblance to a goat.
The eldest child of Mrs. Rumsford. Annabelle has a rag doll named Priscilla, and is described as having blonde curls.
The priest at Holy Trinity. He decides whether or not an abandoned child is allowed to enter the orphanage.
A dog trainer who works in the circus.
Captain Obidiah Smith
The captain of The Liberty during Marie-Grace's trip in The Hidden Gold.
A seamstress who was seen in The Haunted Opera making costumes for the chorus members of Foxcroft's London Opera Company.
A classmate of Marie-Grace Gardner at St. Teresa's Academy. She is one of Lavinia Halsworth's friends.
A pilot aboard The Liberty and a friend of Thaddeus Gardner.
The mother of Susannah Stewart. She was only seen in Marie-Grace and the Orphans, in which she was mentioned to have contracted yellow fever later in the story.
A young girl seen visiting Dr. Gardner's office in Marie-Grace and the Orphans. Mrs. Stewart faints when Dr. Gardner is removing a splinter in her foot, so Dr. Gardner asks Marie-Grace to distract Susannah. Marie-Grace uses her skills from her voice lessons to sing a song with her.
Octavia Tay's husband and Cécile's uncle. Henry died in an accident at the shipyard in Philadelphia where the Tays lived mid-year 1852.
A member of Foxcroft's London Opera Company.
A woman of color who owns a candy shop. She is renowned for her pralines, and Cécile and her grandfather like to stop by the shop for them.