Lady Sybil Branson is a fictional character from the popular British television series Downton Abbey. She is the youngest daughter of the Earl of Grantham and Cora Crawley, known for her strong-willed and progressive nature. Sybil is passionate about social issues and is particularly interested in nursing, which leads her to become a volunteer during World War I. Throughout the series, Lady Sybil's character evolves as she challenges traditional norms, especially regarding her marriage to Tom Branson, the family's former chauffeur. Their relationship highlights themes of class and social change, making her a significant figure in the narrative of Downton Abbey.