Ivan IV was the son of
Tsar Vasily III of
Russia and became tsar, sort of, at the age of three when his father died. His mother the
Lithuanian princess Helena, was his regent with the help of her uncle Michael and her lover Prince Telepnev-Obolensky; however, her marriage to Vasily had not been popular and the boyar
nobles of Russia opposed her rule. Helena died in
1538, most likely by poison, and the boyars fought among themselves for power. Ivan and his younger brother Yuri were
afterthoughts, not well taken care of; Ivan later wrote that "they fed us as though we were foreigners or the most wretched servants. We lacked food and clothing; our will counted for nothing and no one was found to provide for us as children."
Ivan nonetheless managed to educate himself, reading everything he could find (which wasn't much in 1500s Russia -- religous works and chronicles of Russian heroes). From this and from the fighting around him, he came to the view that strength, even to the point of arrogance and cruelty, would serve him best. He tortured animals, broke the leg of a boyar's child in a fight, and raped at least one servant girl. At the age of 14, he decided to take back the power due to the Tsar by having the leading boyar Andrei Shuisky thrown to a pack of dogs and many more boyars hung. Within the next few years, he consolidated his power and married Anastasia Romanov in 1547 (a popular choice, as she was Russian, but he had earlier sought to marry a foreign princess.)
Anastasia and Ivan were a good match, and she is considered to have been a brake on his more outrageous tendencies. In 1550 Ivan put together the Zemsky Sobor, a group of representative from different parts of the country which served as a kind of advisor to the tsar. He set up a new legal code with local government reform, giving more local control to the spread-out parts of Russia. He standardized the military service owed to the tsar by nobles. On the other hand, he put in place laws forbidding Russians to travel abroad and other infringements on personal liberty.
The usual menace to Russia of Tartars on the southeast continued; Ivan managed to capture the city of Kazan on the Volga river, making Russian trade into their new (since the reign of Ivan III) Siberian colonies much easier. Later he would try to conquer the entire length of the Volga down to the Caspian Sea. He was also involved in wars with Livonia (approximately modern Latvia/Estonia) and when its government collapsed, with Sweden and Poland/Lithuania who also wanted possession of the area.
In 1553 English traders trying to reach China arrived on the coast of the White Sea; they were brought to Ivan and started both diplomatic and trade relations between Russia and faraway England. These western connections would grow greatly over the next four centuries.
Also in 1553, Ivan fell ill and on what he thought was his deathbed, asked the boyars to swear allegiance to his infant son. Many of them refused or were at least reluctant, just having gotten out of the turmoil of having an infant for Tsar who could not control the country. Ivan never forgot this, and this increased his mistrust of his nobles even more.
In 1560, Ivan's wife Anastasia died; this is often considered the start of the worst part of Ivan's reign. Ivan was convinced (with no real evidence) that she had been poisoned and tried two of his advisors for the crime without allowing them to defend themselves. He would have six more wives (ignoring the Orthodox Christianity limit of three) but none of them ever calmed him down like Anastasia.
In 1564 he left Moscow and from a small town issued a manifesto saying the nobles and clergy were all derelict in their duty and that he was going to abandon his throne. A delegation led by the Archbishop of Novgorod went to ask him to return, and Ivan agreed with some peculiar conditions. He said he was going to divide the country into two sections, the zemshchina, which would remain as it had been, and the oprichnina, which would have its own court, nobles, and rules. The oprichnina took up part of Moscow and about 20 other towns and districts (not necessarily all together in one area), and former owners of land there were evicted and sent elsewhere. He named a puppet Tsar for the Zemshchina, a Tartar called Simeon who had converted to Orthodox Christianity, but kept the control of both divisions. In the oprichnina his servants were given complete immunity from charges of any crime they committed. The Oprichniks, Ivan's men dressed in black and riding on black horses, killed, tortured, and stole from people in all parts of Russia. The oprichnina was officially abolished in 1572 but was not really reincorporated into the rest of the country for some years, and it didn't stop the arbitrary execution, frequently in disgusting ways, of anyone Ivan suspected.
Ivan would have fits of religious conscience alternating with his periods of paranoia and rage. The worst came after 1581, when Ivan killed his own grown son Ivan. It was in a fit of anger, after the older Ivan had attacked the younger Ivan's pregnant wife for not wearing the customary clothing for a pregnant woman. The younger Ivan tried to defend his wife, and his father hit him with a pointed staff and mortally wounded him, though it took days to for him to actually die. (The wife and baby also died.) Ivan is said to have "known no peace" from his remorse after this.
Ivan died in 1584; a Soviet-performed autopsy is said to have indicated that he was poisoned. This is not very surprising for a ruler who earned the nickname of "Terror-Inspiring," the older sense of "terrible." Some scholars have argued that "Awe-Inspiring" might be a better translation of the nickname; this goes along with the historical dispute about whether Ivan's peculiarities and atrocities were actually helpful for uniting Russia under one central ruler. Some views (including Stalin's) consider Ivan to be a good ruler; others think he was just insane. Ivan was succeeded by his son Fyodor I.
Source: Carr, Francis. Ivan the Terrible. Barnes & Noble Publishing, 1981, in addition to those listed under Monarchs of Russia.