Lee Seon-joon is a fictional character from the popular South Korean television series The Scholar Who Walks the Night. He is portrayed as a nobleman during the Joseon Dynasty, known for his intelligence and strong sense of justice. His character often grapples with the challenges of his society while navigating complex relationships. In the series, Lee Seon-joon becomes involved with Kim Sung-yeol, a vampire scholar, and Yang Sun, a young woman who disguises herself as a man. His journey explores themes of love, loyalty, and the struggle against corruption in a historical context.