Direct Antonyms:
* Autocracy: Rule by a single, absolute ruler.
* Dictatorship: Rule by a single person or a small group, with absolute power.
* Tyranny: Cruel and oppressive government.
* Oligarchy: Rule by a small, elite group.
Indirect Antonyms (emphasizing different aspects):
* Elitism: Belief that a select few are superior and should rule.
* Aristocracy: Rule by a privileged class.
* Theocracy: Rule by religious leaders.
* Totalitarianism: A system of government that controls all aspects of life.
* Authoritarianism: Rule by a single leader or party with strong, centralized power.
* Colonialism: Rule by a foreign power over another territory.
Other possibilities:
* Oppression: The act of ruling unjustly or cruelly.
* Suppression: The act of preventing people from exercising their rights.
* Control: The act of exerting power over others.
The best antonym will depend on the specific context and what aspect of popular sovereignty you want to oppose.