Sóror Mariana Alcoforado was a Portuguese nun living in the convent of the Poor Clares (Convento de Nossa Senhora da Conceição, Convent of Our Lady of the Conception) in Beja, Portugal. Debate continues as to whether Mariana was the real Portuguese author of the Letters of a Portuguese Nun, a collection of five love letters to the French officer Noël Bouton, Marquis de Chamilly and later Marshal of France.