The Lady of the Forest is a lady of the Fair Folk who appears to various characters in the series. In Daughter of the Forest, she guides Sorcha along her destined path in life and tasks her with breaking the spell over her brothers by weaving garments of starwort. Later, she appears to Sibeal. She is described as being extremely tall and beautiful, with long dark hair and a cloak of midnight blue, and is very sympathetic and grave. However, because she is of the Fair Folk she has a different view of the importance of humankind and the world in general, seen when she tells Sorcha to get over her rape and move on to continue her task. There is a tale told of her in Erin that is one of Sorcha's favourite tales.   

After the events of Child of the Prophecy, she like the other Fair Folk leave Erin for the western seas.