The Lady of the Lake
The Lady of the Lake is the name of a character, a poem and various plays
Also found as Lady of the Lake
The character
"The Lady of the Lake" is an enchantress, a character in the Arthurian legends. She is a central figure in many of the stories, being the one who gives Arthur his sword Excalibur, enchants Merlin, and raises Lancelot after the death of his father. Given many names by various writers and copyist (e.g. Nimue, Nymue, Nimueh, Viviane, Vivien, Vivienne, Ninianne, Nivian, Nyneve, or Evienne), she is more generally known simply as "The Lady of the Lake".
She also appears as a character in both the film and stage play of Monty Python's Spamalot
The poem by Sir Walter Scott
The Lady of the Lake is a narrative poem by Sir Walter Scott, written in August 1809 while holidaying with his wife in the Trossachs in Scotland, and along the shores and islands of Loch Katrine. It was first published in 1810. The poem was tremendously influential in the nineteenth century, and inspired what is known as the Highland Revival.
See https://en.wikipedia.org/wiki/The_Lady_of_the_Lake_(poem)
Dramatised versions of the tale and the poem
A number of theatrical versions have been done of it over the years.
Rossini’s opera La Donna Del Lago.
The Lady of the Lake by Benjamin Askew (This production played at the Theatre by the Lake, Cumbria, from 13 June - Fri 6 November 2015)