- His eldest son, Ivan Ivanovich: Ivan the Terrible killed his own son in a fit of rage in 1581.
- His cousin Vladimir Andreyevich Staritsky: Vladimir was a potential rival to Ivan and was poisoned on Ivan's orders in 1569.
- His advisor and friend Prince Andrei Kurbsky: Kurbsky defected to Poland in 1564 and wrote scathing letters against Ivan, prompting Ivan to declare him a traitor and confiscate his estates.
- The Novgorod massacre: In 1570, Ivan led a brutal campaign against the city of Novgorod, suspecting the people of treason. Thousands of people were killed, including innocent civilians.
- The oprichnina: The oprichnina was a special state force established by Ivan in 1565 to eliminate internal enemies. Its members committed numerous atrocities and mass executions of suspected traitors and their families.
Overall, Ivan the Terrible's cruelty and paranoia extended to many individuals and groups, resulting in countless deaths and a climate of fear and terror during his reign.