In Malory’s Mane d’Arthur, the Lady of the Lake is a supernatural figure who lives in a magical lake.
She steals the infant Lancelot and raises him in the lake, hence his name, Lancelot du Lac.
She also awards King Arthur the sword Excalibur, which he takes from an arm reaching out of the lake.
The Lady of the Lake is also a poem by Sir Walter Scott (1771-1832).