Colonel William Kelsey Lanman Jr., (October 9, 1904 – March 26, 2001) was an American philanthropist and benefactor of Yale University.

He served as an aviator in the United States Marine Corps from 1935 to 1955, and later took up real estate and investment management.

from Sheffield Scientific School), as had his ancestor United States Senator James Lanman, who graduated from Yale College in 1788.

He served in the Pacific theater during World War II, with South Pacific Combat Air Transport Command (SCAT) where he was executive officer of the legendary World War II "Flying Boxcar" SCAT squadron.

He received the Distinguished Flying Cross, four Air Medals, a Bronze Star and a U.S. Navy Commendation for action in the Solomon Islands campaigns.