Where did the nicknames of Russian rulers come from

Who came up with calling Prince Oleg - 'the Wise'? What was Tsar Ivan Vasilievich called 'the Terrible' for and why was Catherine - 'the Great'? We'll tell you where the most popular nicknames of historical personalities came from.

Oleg the Wise

One version of how Prince Oleg, the successor of Rurik, got