The House of Romanov (also transcribed Romanoff; Russian: Романовы, tr. Románovy, IPA: [rɐˈmanəvɨ]) was the reigning imperial house of Russia from 1613 to 1917. They achieved prominence after the Tsarina, Anastasia Romanova, was married to the First Tsar of Russia, Ivan the Terrible. In 1924 Grand Duke Kirill Vladimirovich, the senior surviving male-line descendant of Alexander II of Russia by primogeniture, claimed the headship of the defunct Imperial House of Russia. Since 1991 the succession to the former Russian throne has been in dispute.