In the Vulgate Lancelot, the "Dame du Lac" is a fairy that bears away Lancelot to raise him until his eighteenth birthday when she presents him at the court of King Arthur. In Malory, Arthur is given Excalibur by a mysterious personage who holds over the "damsels of the lake," one of whom is Nimue (or Viviane with many variations), the captor of Merlin. While having powers of magic, she is most definitely human and becomes the successor of the Lady that presented Excalibur to the King when that Lady is slain by Balin. Whoever is in the role of the Lady she is beneficent to Arthur, aiding him occasionally with magic. Nimue is among the ladies that bear Arthur to Avalon after the final battle.
Lady of the Lake
Otherworldly affiliated enchantress possibly originating from an archetype of a Celtic priestess. The name suggests a part played by more than one individual. Several Ladies are found in the literature in differing circumstances but they are almost indistinguishable from one another and there is no geographically identifiable lake.