Eleanor the "Fair Maid of Brittany" (c. 1184 – 10 August 1241) was a member of the nobility of England. She was the eldest daughter of Geoffrey Plantagenet and Constance, Duchess of Brittany. She was seen as a potential threat to the throne by her uncle, John of England, and cousin, Henry III of England. She was put in prison from 1202, and so became the longest imprisoned member of an English royal family. Although still treated honorably as a princess, she was never released or permitted to marry.