Russian Empire
Though the Empire was only officially proclaimed by Tsar Peter I following the Treaty of Nystad (1721), some historians would argue that it was truly born either when Ivan III of Russia conquered Veliky Novgorod in 1478, or when Ivan the Terrible conquered the Khanate of Kazan in 1552. According to another point of view, the term "Tsardom", which was used after the coronation of Ivan IV in 1547, was already a contemporary Russian word for empire.
House of Romanov
The Romanovs achieved prominence as boyars of the Grand Duchy of Moscow, later the Tsardom of Russia. In 1613, following years of interregnum (Time of Troubles), the "zemsky sobor" offered the Russian crown to Mikhail Romanov. He acceded to the throne as Michael I, becoming the first Tsar of Russia from the House of Romanov. His grandson Peter I established the Russian Empire and transformed the country into a continental power through a series of wars and reforms.