The Romans, and to a lesser extent, the Greeks, always had one person who had the most power, a Figurehead if you will, nearly every government had this, regardless of what type of government it is.

Julius Ceaser was the Ceaser in Rome and carried much power, but he focused on conquering land so every one was okay with, except the people who killed him.

Chancellor Palpatine was the head of the old republic in it's dying decade, while traditionally the Chancellor has little direct power, Palpatine granted himself emergency powers during the war. Only to serve his own agenda

Darth Vader was the face of the Empire, and while he did wield enormous power, he was really just a pawn to the Emperor.

The Ethereals, over many years, amassed an army of different alien species from sectoids to cyberdisks, they are the ultimate leaders of the cllective, but there are hits of a higher power.

The One Earth government had many high ranking metahumans, from wonder woman to yellow lantern, but all authority was beneath the high counciler, Superman.