For 10 points,  identify this first tsar of Russia, who is probably best known for his rampant acts of cruelty.
During his reign, a military campaign to retake western Slavic lands in the Livonian War  ended badly. He created a secret police organization called the oprichnina, and he held the first zemsky sobor, or parliament. His successor was the simple-minded Feodor I, since he had earlier killed his heir-to-be Ivan Ivanovich, essentially bringing about the downfall of the Ruriks, and his  title may have come from his terrible treatment of the boyars, or the landed elite. For 10 points,  identify this first tsar of Russia, who is probably best known for his rampant acts of cruelty.
During his reign, a military campaign to retake western Slavic lands in the Livonian War  ended badly.
Ivan IV Vasilyevich or Ivan the Terrible or Ivan Grozny