Grand Duke Sergei Alexandrovich of Russia, fifth son and seventh child of Tsar Alexander II (born 1857)

Grand Duke Sergei Alexandrovich of Russia was the fifth son and seventh child of Emperor Alexander II of Russia. He was an influential figure during the reigns of his brother Emperor Alexander III of Russia and his nephew Emperor Nicholas II, who was also his brother-in-law through Sergei's marriage to Elisabeth, the sister of Empress Alexandra.

Tsar is a title historically used by Slavic monarchs. The term is derived from the Latin word caesar, which was intended to mean emperor in the European medieval sense of the term—a ruler with the same rank as a Roman emperor, holding it by the approval of another emperor or a supreme ecclesiastical official—but was usually considered by Western Europeans to be equivalent to "king".

Alexander II was Emperor of Russia, King of Poland and Grand Duke of Finland from 2 March 1855 until his assassination in 1881. Alexander's most significant reform as emperor was the emancipation of Russia's serfs in 1861, for which he is known as Alexander the Liberator.

February 17 is the 48th day of the year in the Gregorian calendar; 317 days remain until the end of the year.