Ivan the Terrible, Russian ruler (d. 1584)
Ivan IV Vasilyevich (Russian: Ива́н Васи́льевич; 25 August 1530 – 28 March [O.S. 18 March] 1584), commonly known in English as Ivan the Terrible (from Russian: Ива́н Гро́зный​ , romanized: Ivan Grozny, lit. "Ivan the Formidable" or "Ivan the Fearsome", Latin: Ioannes Severus, monastic name: Jonah), was the grand prince of Moscow from 1533 to 1547 and the first Moscow ruler who declared himself Tsar of all Russia from 1547 to 1584.

Ivan was the first Moscow ruler born after its independence. The son of Vasili III, the Rurikid ruler of the Grand Duchy of Moscow, he was appointed grand prince after his father's death when he was three years old. A group of reformers known as the "Chosen Council" united around the young Ivan, declaring him tsar (emperor) of All Rus' in 1547 at the age of 16 and establishing the Tsardom of Russia with Moscow as the predominant state. Ivan's reign was characterised by Russia's transformation from a medieval state to an empire under the tsar but at an immense cost to its people and its broader, long-term economy.

During his youth, there was a conquest of the khanates of Kazan and Astrakhan. After he had consolidated his power, Ivan rid himself of the advisers from the "Chosen Council" and triggered the Livonian War, which ravaged Russia and resulted in the loss of Livonia and Ingria but allowed him to establish greater autocratic control over Russia's nobility, which he violently purged with the Oprichnina. The later years of Ivan's reign were marked by the Massacre of Novgorod and the burning of Moscow by Tatars.

Contemporary sources present disparate accounts of Ivan's complex personality. He was described as intelligent and devout but also prone to paranoia, rage, and episodic outbreaks of mental instability that increased with age. In one fit of anger, he murdered his eldest son and heir, Ivan Ivanovich, and he might also have caused the miscarriage of the latter's unborn child. This left his younger son, the politically ineffectual Feodor Ivanovich, to inherit the throne, a man whose rule and subsequent childless death directly led to the end of the Rurikid dynasty and the beginning of the Time of Troubles.