Isaac E. Ditmars, FAIA, was a Canadian-American architect and founding associate of William Schickel & Company, and directed that company as Schickel & Ditmars from 1907 into the 1920s. He joined the American Institute of Architects in 1895 and became a fellow that year. He died in 1935. In 1913, he designed a six-story brick hospital at 430-432 West 164th Street for the Sisters of Charity of St. Vincent De Paul and Mt. St. Vincent on Hudson for $500,000. There was an architect named , architect of the , now the (1869–1870), who may be related.