Nellie Blanchan De Graff (October 23, 1865 - 1918) was a United States scientific historian and nature writer who wrote books on gardening and birds using the penname Neltje Blanchan. Her work is known for its synthesis of scientific interest with poetic phrasing.
She married Frank Nelson Doubleday. They had two sons: Felix Doubleday (adopted) and Nelson Doubleday (1889-1949). Her grandson Nelson Doubleday Jr. purchased the New York Mets in 1986. Some of her papers (1914-1918) are in the Frank N. Doubleday and Nelson Doubleday Collection at the Princeton University Library. There is a Neltje Blanchan Literary Award given by the Wyoming Arts Council, which is given annually to "a writer whose work, in any genre, is inspired by nature."