Cornelis Sebille Roos or Cornelis Roos (1754 – 1820) was a Dutch art dealer and inspector of the Nationale Konst-Gallery collection in Huis ten Bosch during the years 1799-1801
Roos was born 10 January 1754 in Amsterdam and baptized six days later in the Walloon church. He became a drawing teacher and manager of Felix Meritis, which he helped found. In 1798 he lived in the left-hand side of the Trippenhuis where he started his art dealership. Many of the paintings he originally purchased have found their way into the collection of the Rijksmuseum. He was friends with Jan Gildemeester and attended the estate sale of his art collection, buying many pieces there that later found their way in the Huis ten Bosch collection. The most notable of these was The Threatened Swan by Jan Asselijn, which became the first painting purchased by the director of the Nationale Konst-Gallery, Alexander Gogel. The painting, which is not dated, was painted before the events which caused it to be marked. It was marked to make it a political allegory of the patriot hero Johan de Witt who was murdered by orangists. Since Roos was known for his patriotic politics, it is quite possible that he marked the painting himself when he bought it in 1800, though the estate sale catalog already mentions that it is an allegory of Johan de Witt.
