despot

noun2

1. •
   A ruler with absolute power; a tyrant.

   • The Red Holocaust is best interpreted in this light as the bitter fruit of an^([sic]) utopian gambit that was socially misengineered into a dystopic nightmare by despots in humanitarian disguise. — 2009
2. •
   (historical) A title awarded to senior members of the imperial family in the late Byzantine Empire, and claimed by various independent or semi-autonomous rulers in the Balkans (12th to 15th centuries)