Rebecca Henriette Lejeune Dirichlet, née Rebecca Henriette Mendelssohn Bartholdy (11 April 1811 – 1 December 1858) was a granddaughter of Moses Mendelssohn and the younger sister of Felix Mendelssohn Bartholdy and Fanny Hensel.

Rebecca was born in Hamburg. She became the centre of a notable salon, having social contacts with the important musicians and scientist in a highly creative period of German intellectual life.

In 1832 she married the mathematician Peter Gustav Lejeune Dirichlet, who was introduced to the Mendelssohn Bartholdy family by Alexander von Humboldt. She died in Göttingen.

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