Konstanty Jelski (February 17, 1837–November 26, 1896) was an acclaimed Belarus-born Polish ornithologist and zoologist. Born in the village Liady, today's Smalyavichy Raion of Minsk Governorate (in present-day Belarus), he conducted many important studies abroad, specifically in French Guiana and Peru from 1866 to 1875. He was the curator of a museum in Lima from 1874 to 1878, when he came Poland to become the curator of the Natural History dep. of Academy of Learning in Kraków.