Grand Duchess Olga Nikolaevna of Russia (Olga Nikolaevna Romanova) (Russian: Великая Княжна Ольга Николаевна; IPA: [vʲɪˈlʲikəjə knʲɪˈʐna ˈolʲɡə nʲɪkɐˈlaɪvnə] (Velikaya Knyazhna Ol'ga Nikolaevna); November 15 [O.S. November 3] 1895 – July 17, 1918) was the eldest daughter of the last Tsar of the Russian Empire, Emperor Nicholas II, and of Empress Alexandra of Russia.

During her lifetime, Olga's future marriage was the subject of great speculation within Russia. Matches were rumored with Grand Duke Dmitri Pavlovich of Russia, Crown Prince Carol of Romania, Edward, Prince of Wales, eldest son of Britain's George V, and with Crown Prince Alexander of Serbia. Olga herself wanted to marry a Russian and remain in her home country. During World War I, Olga nursed wounded soldiers in a military hospital until her own nerves gave out and, thereafter, oversaw administrative duties at the hospital.

Olga's murder following the Russian Revolution of 1917 resulted in her canonization as a passion bearer by the Russian Orthodox Church. In later years, when dozens of people made claims to be surviving members of the imperial family, a woman named Marga Boodts claimed to be Grand Duchess Olga, but her claim was not taken seriously. Olga was assassinated along with her family at Yekaterinburg. Her remains were identified through DNA testing and were buried during a funeral ceremony in 1998 at Peter and Paul Cathedral in St. Petersburg along with those of her parents and two of her sisters.