You can consider the following set of words:
supreme authority or power.
of or relating to a governmental or political system, principle, or practice in which individual freedom is held as completely subordinate to the power or authority of the state, centered either in one person or a small group that is not constitutionally accountable to the people.
of or relating to a centralized government that does not tolerate parties of differing opinion and that exercises dictatorial control over many aspects of life.
[References - Dictionary.com]
Note that authoritarian and totalitarian are synonymous with neutral to negative connotation.