Ellen "Nelly" Thayer Fisher (April 16, 1847 – October 15, 1911) was an American botanical illustrator. Fisher exhibited her paintings at the National Academy of Design and other exhibitions. She was an active contributor to the exhibitions of the American Watercolor Society, beginning in 1872. In addition to being shown in galleries and exhibitions, her paintings of flora and fauna were widely reproduced as chromolithographs by Boston publisher Louis Prang.