Diana Olivia Winifred Maud Cooper, Viscountess Norwich (née Lady Diana Manners; 29 August 1892 – 16 June 1986) was an English aristocrat who was a well-known social figure in London and Paris. As a young woman, she moved in a celebrated group of intellectuals known as the Coterie, most of whom were killed in the First World War. She married one of the few survivors, Duff Cooper, later British ambassador to France. After his death, she wrote three volumes of memoirs which reveal much about early 20th-century upper-class life.