The term 'The Terrible' is a nickname for IVAN IV of Russia, who was also known as IVAN the Terrible. He was the first Tsar of Russia and reigned from 1533 to 1584. His nickname was derived from his reputation for being a cruel ruler. He was also known as IVAN Grozny, which translates to IVAN the Formidable or IVAN the Fearsome. He was known for his military campaigns and expansion of the Russian Empire. He was also responsible for the establishment of the Oprichnina, a secret police force that was used to suppress dissent.