What was the name of the maiden who loved Lancelot and died of a broken heart?

The maiden who loved Lancelot and died of a broken heart was Elaine of Astolat.

Elaine is a lady of Astolat, also called Escalot or Ascolat in different versions of the legend. In the early 13th-century French romance Mort Artu, she dies from unrequited love for Lancelot and is placed in a boat that drifts toward Camelot. Sir Thomas Malory retold the episode in Le Morte d’Arthur, published in 1485.

In Malory’s version, Elaine falls in love with Lancelot after nursing him when he is wounded at a tournament. Lancelot treats her kindly but does not return her love, because he remains devoted to Queen Guinevere. Elaine dies ten days after he leaves. Her body is sent downriver with a letter explaining her story, prompting the court to call her the “Fair Maid of Astolat.”

She is often confused with Elaine of Corbenic, who is the mother of Galahad. Modern retellings also connect Elaine of Astolat with Tennyson’s Lady of Shalott, though the characters are not identical in every detail.