Who was Julie Guicciardi to whom Ludwig van Beethoven dedicated his "Moonlight Sonata"?

Julie Guicciardi (23 November 1784 – 22 March 1856) was an Austrian countess and briefly a piano student of Ludwig van Beethoven. He dedicated to her his Piano Sonata No. 14, later known as the "Moonlight Sonata".

Julie Guicciardi, as she was named by her family, was born in Przemyśl, Galicia. Her parents were Count Franz Joseph Guicciardi and Countess Susanna von Brunswik. She arrived in Vienna with her parents from Trieste in June 1800, and her beauty caused her to be noticed by high society. She was soon engaged to Count von Gallenberg (1780–1839), an amateur composer, whom she married on 14 November 1803. Subsequently, they moved to Naples. She returned to Vienna in 1822. In later years, Count Hermann von Pückler-Muskau was among her admirers.

She died in Vienna in 1856.

Beethoven became acquainted with Guicciardi through the Brunsvik family (often known in English as "Brunswick"). He was particularly intimate with her cousins, the sisters Therese and Josephine Brunsvik (whom he had taught the piano since 1799). In late 1801, he became Guicciardi's piano teacher, and apparently became infatuated with her.