In 'The Fall of the House of Usher', what is the name of Roderick's twin sister?

In Edgar Allan Poe’s The Fall of the House of Usher, Roderick Usher’s twin sister is Madeline Usher. She and Roderick are the last living members of the Usher family.

Madeline suffers from a mysterious illness that includes cataleptic, deathlike trances. Roderick eventually declares that she has died and places her in a vault beneath the house, but the narrator notices that her body still appears unusually lifelike. The story later reveals that she was buried prematurely.

During a violent storm, Madeline escapes from the vault and returns to Roderick. Her appearance coincides with the climax of the story: Roderick dies in terror, Madeline collapses, and the ancient House of Usher splits apart and sinks into the tarn. Madeline is sometimes confused with Poe’s other famous female figures, such as Ligeia or Lenore, but those characters belong to different poems and tales.