Henry Mills Alden (November 11, 1836 – October 7, 1919) was an American author and editor of Harper's Magazine for fifty years—from 1869 until 1919.

[2] On the day of his graduation he delivered the master's oration at Williams college on the Hellenic type of men; he also wrote the class hymn for Andover.

[1] He located in New York City in 1861, and was employed in teaching and in writing editorials for the daily newspapers and contributing articles to the Atlantic Monthly.

[1] He was known as a classical student of large acquirements, particularly in connection with Greek literature and thought; and his first literary ventures were two articles contributed to the Atlantic Monthly on the Eleusinian Mysteries.

[4] He collaborated with Alfred Hudson Guernsey (1818–1902)[5] in the preparation of Harper's Pictorial History of the Great Rebellion, and as reader of manuscript,[1] from 1862 to 1865.