Read Hobbes' Leviathan, it discusses this. A prerequisite for success the sovereign must establish a state religion, subjects comply or are executed.

And then John Locke, with emphasis on consent of the governed.

And why not the Catholic Church? The pope is essentially what you describe but they have been many bad Popes. Nevertheless as an institution it endures, with and without justice.

A sovereign who is completely selfless would not be a human. So you're necessarily searching for deities or an off worlder. And when they're done? Who then? Sounds chaotic and capricious.