Sarah Hewitt and Eleanor Hewitt, also known as The Hewitt Sisters, were American art advocates and founders of what is today the Cooper Hewitt, Smithsonian Design Museum in New York City. They are the granddaughters of Peter Cooper, an American industrialist, inventor, philanthropist, and founder of the Cooper Union for the Advancement of Science and Art. The sisters first established the museum on the fourth floor of the Cooper Union. They sought to foster American design and appreciation for the decorative arts.