Tristran Thorn is the main character in the novel "Stardust" by Neil Gaiman. He is a young man from the village of Wall, which is named after the stone barrier that separates the mundane world from the magical realm of Faerie. Tristran embarks on a quest to retrieve a fallen star for his beloved, unaware that the star is a living being. Throughout his journey, Tristran encounters various magical creatures and challenges, ultimately discovering his true identity and purpose. His character evolves as he learns about love, sacrifice, and the complexities of both the human and magical worlds.