* Eleanor of Aquitaine (1122-1204): This queen consort to both Louis VII of France and Henry II of England was a powerful figure in her own right. She was a wealthy and influential landowner, a patron of the arts, and a major player in medieval politics. She had a huge influence on the development of English culture and her sons, including Richard the Lionheart and John, became key figures in English history.
* Eleanor of Castile (1241-1290): Queen consort to Edward I, she was a devout Catholic and a skilled administrator. She founded hospitals and religious houses and her influence on Edward I's reign was significant, particularly in areas like legal reform and the development of the English parliament.
* Eleanor of Provence (1223-1291): Queen consort to Henry III, she was a controversial figure, but nonetheless a major player in English politics. She was a skilled diplomat and was involved in attempts to resolve disputes with the French and the Welsh.
* Eleanor of Lancaster (1318-1372): The daughter of Henry, Duke of Lancaster, she was a strong and determined woman who played an important role in the Hundred Years' War. She was involved in the Battle of Neville's Cross and was a key supporter of her son, John of Gaunt.
* Eleanor Cobham (1393-1452): The mistress, and later wife, of Humphrey, Duke of Gloucester, she was a powerful and influential figure during the Wars of the Roses. She was accused of witchcraft and treason and was eventually imprisoned.
To give you a more specific answer, please clarify which "Eleanor" you are interested in.