Ten-year-old Harvey Swick is the protagonist and hero of The Thief of Always. He begins the story bored with his life and longing for adventure. He is tired of following the rules of adults and is excited when he is introduced to Holiday House, a paradise for children, where they can eat, play, and enjoy whatever they want. He soon realizes, however, that Holiday House is an illusion and that the children who go there are harmed.
Wendell is a boy that Harvey befriends at Holiday House. Wendell is in his element in the house; he thrives on excess and sees no downfall to being able to live out his desires. Even when the illusion of the house is revealed to Wendell, he prefers to live in the fantasy than return to reality.
Mr. Hood is the owner of Holiday House. He is a Willy-Wonka figure in that he is mysterious but appears to thrive on granting children's fondest wishes. Harvey discovers that Mr. Hood is enticing children through the fantasy of Holiday House before stealing their souls (time) from them.
Mrs. Griffin is the housekeeper and cook at Holiday House. She makes sure everything runs smoothly and is motherly towards the children. However, Harvey discovers that she is facilitating Mr. Hood's kidnapping of children for her own reasons.
Mr. Hood has several servants in the house to make it run smoothly. Rictus is his head servant and is the one who solicits children for Holiday House.