Nadezhda Yakovlevna Mandelstam (Russian: Надежда Яковлевна Мандельштам, nee Hazin; October 18, 1899 — December 29, 1980) was a Russian writer and a wife of poet Osip Mandelstam.

Born in Saratov into a middle-class Jewish family, she spent her early years in Kiev. After the gymnasium she studied art.

After their marriage in 1921, Nadezhda and Osip Mandelstam lived in Ukraine, Petrograd, Moscow, and Georgia. Osip was arrested in 1934 for his Stalin epigram and exiled to Cherdyn, Perm region and later to Voronezh, and his wife joined him there. After Osip Mandelstam's second arrest and his subsequent death at a transit camp "Vtoraya Rechka" near Vladivostok in 1938, Nadezhda Mandelstam led almost nomadic way of life, dodging her expected arrest and frequently changing places of residence and temporary jobs. On at least one occasion, in Kalinin, the NKVD came for her the next day after she fled.

As her mission in life, she set to preserve and publish her husband's poetic heritage. She managed to keep most of it memorized because she didn't trust paper.

After the death of Stalin, Nadezhda Mandelstam completed her dissertation (1956) and was allowed to return to Moscow (1958). In her memoirs, first published in the West, she gives an epic analysis of her life and criticizes the moral and cultural degradation of the Soviet Union of the 1920s and later.

In 1979 she gave her archives to Princeton University. Nadezhda Mandelstam died in 1980 in Moscow.

• Hope against Hope (ISBN 1860466354) (wordplay: nadezhda means "hope" in Russian language)
• Hope Abandoned (ISBN 0689105495)