Russian Empire
The Russian Empire was one of the largest countries that has ever existed, and the third-largest empire in history behind the British and Mongol Empires. It rose with the decline of other notable powers like the Swedish Empire, the Polish–Lithuanian Commonwealth, Qajar Iran, the Ottoman Empire, and the Qing dynasty. The Empire's foundations were built by Ivan III of Russia, Grand Prince of Moscow and all Russia, who established this vast Russian state, declaring independence from the Tatars. Ivan the Terrible, his grandson, went on to become the first Tsar of all Russia.
As the Rurikids declined, the House of Romanov rose; Siberia was conquered, and Peter the Great fought against the Ottomans and Swedish, moving the capital to Saint Petersburg near Lake Ladoga. Catherine the Great continued expansion, while Emperor Alexander I helped beat Napoleon and the French. The Holy Alliance was later formed with good friends Prussia and Austria—eventually, a reboot by the name of the League of the Three Emperors would drop. Then the Empire beat Türkiye only to lose to them in Crimea, expanded into Central Asia, and see numerous reforms by Emperor Alexander II.
At one point, the Empire controlled parts of North America, including Alaska. Now, as big as it seems, monarchies like this one had major flaws. After a vast famine, much of the Russian public began feeling skeptical of their empire. After the Russian Revolution of 1905, Emperor Nicholas II came up with the State Duma. But even then, he would go on to be the last emperor in its history; numerous defeats around World War I saw a major spike in skepticism. In 1917, the February Revolution successfully led to Nick's abdication and the beginning of the short-lived Russian Republic; this marked the series finale of the Russian Empire.