"Lady of the Lake" is the title given to the high priestess and head of the druid religon. She holds court from the holy island of Avalon.

Vivien or Viviane - Aunt to Arthur and Morgaine or Morgan le Fay (both mothered by Igraine.)

Viviane was mother to Lancelot, but did not raise him. (Lancelot was raise by his father, a lesser King in brittany.)

Viviane did give Arthur Excalibur and a magic scabbard constructed by Morgaine to protect Arthur from mortal wound. (She later reclaimed the scabbard and Arthur was mortally wounded soon after.)

Balin was her son. She was killed by Balin's foster brother after Balin was killed in battle.

Nimue was Viviane's granddaughter. (Her father was Lancelot.) She was not Lady of the Lake. She did seduce Kevin the Bard, Merlin of Britain (he had become treasonous to the druids). She later killed herself after the death of the Merlin.

There were two distinct women who held the title Lady of the Lake; Viviane and Morgaine.