Fanny Mendelssohn (14 November 1805 – 14 May 1847), later Fanny [Cäcilie] Mendelssohn Bartholdy and, after her marriage, Fanny Hensel, was a German composer and pianist from the Romantic era. She grew up in Berlin, Germany, and received a thorough musical education from teachers including her mother, Ludwig Berger, and Carl Friedrich Zelter. Her brother Felix Mendelssohn, also a composer and pianist, shared the same education and the two developed a close relationship. Due to the reservations of her family, and to social conventions of the time about the roles of women, a number of her works were published under her brother's name in his Opus 8 and 9 collections. In 1829, she married the artist Wilhelm Hensel and, in 1830, the two had their only child, Sebastian Hensel. In 1846, despite the continuing ambivalence of her family towards her musical ambitions, Fanny Hensel published a collection of songs as her Opus 1. The next year, she suddenly died of a stroke.
She composed over 460 pieces of music, including a piano trio, a piano quartet, an orchestral overture, four cantatas, over 125 pieces for the piano, and over 250 lieder, most of which went unpublished in her lifetime. Since the 1990s her life and works have been the subject of more detailed research. Her Easter Sonata was inaccurately credited to her brother in 1970, before analysis of new documents in 2010 corrected the error.