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."

Published works

• Bird Neighbors (1897)
• Birds That Hunt and Are Hunted
• Nature's Garden (1900)
• "What the Basket Means to the Indian," a chapter in Mary White's How To Make Baskets (1901)
• Birds Every Child Should Know (1907)
• The American Flower Garden (1909)
• Wild Flowers: An Aid to Knowledge of our Wild Flowers and their Insect Visitors (1916)
• Wild Flowers Worth Knowing (adapted by Asa Don Dickenson, 1917, 1922)
• Birds: Selected from the Writings of Neltje Blanchan (posthumously, 1930)