Nimune/Vivianne is a beautiful young woman. She embodies the qualities of feminine youth; she is gentle, caring, curious, and above all beautiful, with the shapely figure of a woman in her youth. Nimune is the goddess of healing and inspiration, as well as, of course, the moon. She resides in the Holy Healing Spring known to mortals as 'The Lake', which has given her the name 'Lady of the Lake'. It was she who gave the grand sword Excalibur to King Arthur.
The Lady of the Lake plays a pivotal role in the story of King Arthur and his knights of the Round Table, in giving him his sword Excalibur after his original sword is broken.
She also aids Arthur and his knights to succeed in their endeavors. After the Battle of Camlann Arthur is seriously wounded and is spirited off to Avalon. Sir Bedivere then takes Excalibur and throws it back into the lake as agreed upon at the time it was given to King Arthur. As Excalibur sails through the air the Lady of the Lake rises up out of the water to reclaim the magical sword, after which she disappears once more beneath the water.