William Butler Duncan (17 March 1830 – 12 June 1912) was a Scottish-American banker and railroad executive.

[2] His father came to America as a young man and graduated from Yale University in 1827.

[4] The younger Duncan was a leader in American yacht racing and graduated from the United States Naval Academy in 1882. he served on the USS Yankee in the Spanish–American War.

[3] On 22 November 1853, Duncan married Jane Percy Sargent (1833–1905) in New Orleans.

[9] Together, they lived at 1 Fifth Avenue in New York City and were the parents of:[8] From 1858 to 1896, the Duncan family maintained a residence on Grymes Hill, Staten Island, in the former home of the neighborhood's namesake, Suzette Grymes.