Ivan the Terrible was once a leader who was the first czar of Russia. His insanity and evilness lead to him killing his own son. He then became good. Overcome with remorse and guilt, Ivan began praying shamelessly for forgiveness for his misdeeds; he sent out lists of his victims to various churches, asking the priests to pray for their souls, and shut down the Oprichniki. Ivan died in 1584, and was succeeded by his younger son, who is known today as having been mentally retarded, dimwitted, and childless. The exact cause of his death is unknown, as some people believed he was poisoned by members of the nobility; however, Ivan was known for consuming mercury, which may have led to his death (it also happened to be one of the root causes of his habitual violent outbursts).
Ivan the Terrible on Real Life Villains wiki
Ivan the Terrible (Night at the Museum) on Villains wiki