Lady of the Lake
The Lady of the Lake, an enchantress also known as Viviane or Nimuë, appears in many of the tales of King Arthur. According to legend, she lived in a castle beneath a lake surrounding the mystical island of Avalon. She raised Lancelot and gave Arthur the magical sword Excalibur, which he treasured. When Arthur was near death, she saved him by taking him to Avalon.
Arthur's magician Merlin fell in love with the Lady of the Lake, but she did not return his affection. However, she did persuade him to teach her some of his magic. While the two were traveling together, the Lady of the Lake used the spells she learned from Merlin to imprison him in a tower with invisible walls (in some versions of the story she traps him in a tree or cave instead).
The Lady of the Lake was also associated with Pelleas, one of the knights of the Round Table. When Pelleas was rejected by Ettard—the woman he loved—the Lady of the Lake took care of him. She and Pelleas fell in love and were married.