Cassie Blake is a fictional character from the book series The Secret Circle by L.J. Smith. She is a teenage girl who discovers her witch heritage after moving to the town of Chance Harbor. Cassie is known for her strong magical abilities and her connection to a group of witches, which includes her friends and fellow witches. In the story, Cassie struggles with the challenges of being a witch, including the responsibilities and dangers that come with her powers. Her character is central to the plot, as she navigates friendships, love, and the complexities of magic in her new life.