Waldron Phoenix Belknap Jr. (May 12, 1899 – December 14, 1949) was an esteemed American figure known for his expertise in art history, architecture, and military service. Born into a wealthy family in New York City, Belknap pursued higher education at Harvard University, where he obtained bachelor's and master's degrees. His military career saw him rise to the rank of captain in the U.S. Army, serving during both World Wars. Belknap's contributions to the field of art history were significant, with his research shedding light on the influences of British portrait engravings on colonial American art. Although he only published one article during his lifetime, his findings significantly impacted the understanding of colonial portrait painting. Belknap's legacy lives on through the Waldron Phoenix Belknap Jr. Research Library of American Painting at the Winterthur Museum, Garden and Library, as well as the Belknap Press imprint established by Harvard University Press. His dedication to art and his generous endowments have left a lasting impact on the art historical community, cementing his place as a respected authority in the field.