Ruth Ellen du Pont Lord (January 14, 1922 – August 4, 2014) was an American writer, psychotherapist, philanthropist, and patron of the arts. Long active in the Yale and New Haven communities, she co-founded Long Wharf Theatre in 1965 and worked at Yale Child Study Center, specializing in psychotherapy and coauthoring a book about foster care. The last private resident of the Winterthur Museum, Garden and Library, she also wrote a biography of her father, Henry Francis du Pont.