Ivan Ivanovich (28 March 1554 – 19 November 1581), of the House of Rurik, was the heir apparent of the Tsardom of Russia, being the second son of Ivan the Terrible and Anastasia Romanovna, and elder brother of Feodor.
Tsarevich Ivan Ivanovich was an affiliate of the Templar Order, resulting in his death at the hands of the Assassins in 1581. Underneath the library of Ivan the Terrible, a portrait of Ivan Ivanovich hid a secret Assassin entrance to the library.
- Historically, Ivanovich was beaten to death by his father with the Tsar's staff, following a heated argument on 15 November 1581. The elder Ivan later regretted killing his son and never forgave himself again. Ivanovich regained consciousness and said that he died a humble son and servant. However, the younger Ivan would live for two more days after his beating, to which the elder Ivan prayed for a miracle, to no avail.