So far from the info we have got, we know a couple of the leaders that some races will have in the game. Some are the leader of an entire faction as well. But for me, some are missing. Not sure if there is even some info on it.

Dunmer: The Tribunal
Nords: Jorunn the Skald king
Argonians: Tribal chief?

Bretons: High king Emeric
Redguards: Some king?
Orsimer: Some warchief?

Altmer: Queen Ayrenn
Bosmer: The Silvenar?
Khajiiti: The Mane most likely

As you can see I have suggested a type of leader for some races that I'm not entirely sure of. But if some people who do know for sure what type of leader there is going to be, than please let me know and if you can add a name to it as well, that would be nice.

afaik Orcs are not a nation.
each settlement and stronghold strives for independence.
imho any kind of Orcish overlord would be very disturbing.