Fanny Geefs (1807–1883) was a Belgian painter of Irish descent.
Born Isabelle Marie Françoise Corr in either Dublin or Brussels, she studied art as a child. In the 1830s she studied with François-Joseph Navez. As well as portraiture, she painted religious and historical scenes such as Our Lady Appearing to the Oppressed which hangs in the Church of the Holy Family in Schaerbeek. She married successful sculptor Guillaume Geefs in 1836.
She worked on commissions for the Belgian royal family, including several portraits of Queen Louise-Marie. Her triptych The life of a woman: Pity - Love - Sorrow was an influence on Charlotte Brontë, in particular her autobiographical novel Villette, set in Brussels.
On her death in 1883 the Royal Library of Belgium purchased a large collection of her works.