William Nelson Cromwell (January 17, 1854 – July 19, 1948) was an American attorney active in promotion of the Panama Canal and other major ventures especially in cooperation with Philippe Bunau-Varilla.

[1][2] He was born and raised in Brooklyn, New York, in an Episcopalian household, by his mother, Sarah M. Brokaw, a Civil War widow.

[5] On June 19, 1902, three days after senators received stamps showing volcanic activity in Nicaragua they voted for the Panama route for the canal.

Another was the founding of "the Society of Friends of Roumania" in 1920 under the patronage of Her Majesty Queen Marie of Romania.

Under his tutelage, the New York-based Society promoted numerous exchanges between the two countries and published the distinguished Roumania – A Quarterly Review.