As a boy, Ivan IV suffered under the regents. While he was treated with respect in public, in private he was often neglected and tortured. He also witnessed the boyars fighting to come to power. These two things are believed to have caused Ivan IV to be cruel. As a child he was known to torture animals, and as an adult his actions earned him the name Ivan the Terrible. He was also very suspicious of the boyars and heavily persecuted them. This too may have been from seeing the actions of the boyars when he was a child.

Ivan IV's reign is usually divided into two parts. During the first half, the good period, Ivan IV ruled with the advise of a council. In 1549 he called together a zemskii sobor, assembly of the land, and then in 1550 established a new law code. He also updated the army and was initially successful in military matters, defending Russia's borders to the east. However, he suffered losses when trying to expand his territories westward.

The second half of Ivan IV's reign is known as the bad period. During this time he discontinued using a council of advisors and became especially suspicious of the boyars. He gained the authority to rule with complete autonomy when he threatened to abdicate the throne but was asked to continue his rule. This threat was calculated by Ivan IV to give him more power, and he got it by agreeing to remain in power but only if he could rule without the moral guidelines of the church.

After this, Russia was divided into two areas. In the region known as the Oprichnina, Ivan IV had sole control. In the other, the boyar Duma was to have direct rule. This agreement was never carried out though, and Ivan IV had sole rule over the entire nation. He used the Oprichniki, a militia which was loyal to him, to terrorize the country. Ivan IV became famous for torturing and executing thousands of people. Even members of the Russian Orthodox church were not exempt from Ivan IV's executions. The church had traditionally been a check on the power of the rulers; however, when church leaders expressed disagreement with Ivan' IV's policies, they were often tortured and executed.

In 1581, Ivan accidentally killed his son Ivan, the heir to the throne, in a fit of rage. On November 16, Ivan IV walked into the apartment of his son and started criticizing his seven month pregnant daughter-in-law Elena, who appeared immodestly dressed. Ivan, so enraged by her unacceptable look, started beating her, what ultimately lead to miscarriage. His son Ivan Ivanovich rose to defend his wife. In a fit of rage, Ivan struck his son dead with his staff.

Mad with sorrow and guilt, he had a dramatic face, posthumously forgiving all those he'd executed and paying for prayers to be said for their souls. Before his death, Ivan was re-christened as the monk Jonah and buried in his monk's habit in the hope of finding ultimate forgiveness.