The Lady of Shalot, Elaine of Astolat is the woman who dies of unrequited love for Lancelot and her body is floated in a barge to Camelot with a letter for Lancelot clutched in her lifeless hand. The Lady of Shalot appears in Malory and in Tennyson's idyll of "Lancelot and Elaine."
The Lady of Shalot story appears in the vulgate Mort Artu and in Malory, but the best-known version is Alfred, Lord Tennyson's "The Lady of Shalott" (original version, 1833; revised version, 1842)
In his poem, Shalot is the home of an unnamed lady who falls in love with Lancelot and dies of grief without him. The body of The Lady of Shalot is floated on a boat down the river to Camelot. In Malory's version her name is Elaine. In his Idylls of the King, Tennyson uses Malory's story including the name "Astolat", Elaine is the "lily maid of Astolat."
In another of Tennyson's writings, The Lady of Shalot is cursed to never look out her window. She is can only look at the world by the reflections in her mirror. The Lady of Shalot passes her time weaving the things she sees in the mirror. One day, the Lancelot passes her window, she is so taken by him that she forgets the curse and looks directly out of the window. Her mirror cracks, the curse is upon her. She goes down to the river, finds a boat, unties it and lays down in the boat. Her blood freezes and she dies. Her boat with her body floats towards Camelot, where Lancelot sees her and says "She has a lovely face: God in his mercy lend her grace, The Lady of Shalot".
Full references to more about The Lady of Shalot at the Rochester site