Arcadie Claret (1826–1897) was a Belgian noblewoman. She was the mistress of Leopold I of Belgium for twenty years, from 1844 until the king's death in 1865. The public affair caused a scandal and attracted great attention in contemporary Belgium. Arcadie had two sons with Leopold, who were ennobled as the Barons d'Eppinghoven by Leopold's nephew, Ernest II, Duke of Saxe-Coburg and Gotha. In 1863 Arcadie was also awarded the title of Baronin von Eppinghoven.