Fanny Mendelssohn (14 November 1805 – 14 May 1847), later Fanny [Cäcilie] Mendelssohn Bartholdy and, after her marriage, Fanny Hensel, was a German pianist and composer, the sister of the composer Felix Mendelssohn and granddaughter of the philosopher Moses Mendelssohn. She was the grandmother of the philosopher Paul Hensel and the mathematician Kurt Hensel.