Well, traditionally the Thalmor rules the Thalmor. The Thalmor proper is something of an oligarchical council made up of Altmer and Bosmer. The Devs may have changed that since then, however.
The 4th era Thalmor, to me, are markedly different from their original predecessors. Perhaps they were just a little bitter after Tibers conquest, as they've seem to have retracted themselves and mutated in Summerset during the course of the 3rd era.