Les XX
Les XX was a group of twenty Belgian painters, designers and sculptors.  It was formed in 1883 by the Brussels lawyer, publisher, and entrepreneur Octave Maus.  For ten years 'Les Vingt', as they called themselves, held a yearly exhibition of their art.  Each year twenty international artists were also invited to be in the exhibition. Artists invited over the years included: Camille Pissarro (1887, 1889, 1891), Claude Monet (1886, 1889), Georges Seurat (1887, 1889, 1891, 1892), Paul Gauguin (1889, 1891), Paul Cézanne (1890), and Vincent van Gogh (1890, 1891).