Jenny Thornton is the protagonist of the series and longtime girlfriend of Tom Locke. At age five she had discovered a dark secret in her grandfather's basement, which had caused the mysterious disappearance of her grandfather and precipitated into her own personal worst nightmare. Years later, needing a game for Tom's birthday, she discovers the More Games store and meets Julian, who seduces her into buying the game, starting a chain of events that brings the game to life and prompts Jenny and her friends to fight for their lives, experiencing their very worst fears. Julian designates her the main player of his games, and thus her friends are dependent on her to progress through each game Julian forces them to participate in. Her nightmare is a reenactment of the events in her grandfather's basement, although this allows her to learn more about what Julian truly is and what had actually become of her grandfather.
Jenny is shown to be a good-hearted, compassionate and kind person, though strong and courageous in her own right; it is these very attributes that Julian is attracted to, seeking to cherish her goodness and keep her with him. Despite her own mutual attraction to the Shadow Man, Jenny deeply loves her boyfriend, Tom, and always chooses him among other things and people. As such, she is later hurt by Tom's withdraw from her in The Chase, and even risks her life to rescue him and Zach from the Shadow World in The Kill.