Countess Alexandra Constantinovna von Zarnekau (Russian: ??????? ?????????? ?????????????? ????????, 10 May 1883 - 28 May 1957) was the eldest daughter of Duke Constantine Petrovich of Oldenburg and his morganatic wife, Agrippina Japaridze, Countess von Zarnekau.
At age 17, on 11 February 1900, Countess Alexandra married Prince George Alexandrovich Yuryevsky, the son of Tsar Alexander II by his mistress (and later wife), Ekaterina Mikhailovna Dolgorukova, the Princess Yourievskya.
They were married at Nice, France, and had one child, Prince Alexander Georgievich Yourievsky, who was born 20 December 1901.
Alexandra and George divorced in 1908.Countess Alexandra married secondly to Leo Vassilievich Narishkin on 17 October 1908 at Paris, France.
During the First World War, Countess Alexandra worked as an administrator of the Russian hospital at Saloniki.