Initially, I was going with Galactic Oligarchy of Bittervets (GOB)
But it has so many elements of Oligarchy, Aristocracy, Feudalism, Stratocracy, Socialism and even Kleptocracy.
EVE empires are inherently Thalassocratic and for one so large to succeed, it needs to be very much consociational.
So fuck it, lets just go for the gold.
I present to you the:
Federation of Aristocratic Republics' Consociational Empire