All of the daedric lords are princes and princesses of certain realms/parts of life. Who is the daedric king or queen?

There is none

I wouldn't normally think of it as such, but I suppose it could be argued that Padomay is the king and queen, as the Daedra came from it. But they don't have a monarch in the traditional sense.

Hmmm......then why are they referred to as being Princes?

That's just what their title is. Even the female ones are Daedric "Princes". Hermaeus Mora doesn't even have a gender, and it's a Daedric Prince.

None are. They are all 'Princes'.
Its either Akatosh or the Godhead.

Technically Akatosh is the 'father' of the divinities. So I'm leaning towards the Godhead

prince used to mean ruler of a land, not son of a king. they are really principalities i suppose, ideas and all that good stuff

I just wiki'd the entire thing. Appearently Sithis and his brother Anu are the chief deities of creation in this fantasy. Their conflict caused 2 lesser spiritual groups to emerge. The Aedra and the, mer dubbed, Deadra. A select few Aedra used their devine energies to create Nirn and the universe around it.

Just to elaborate on this. Sithis, the void, is essentially God. Although he or it is worshipped by the worst people on Nirn, The Dark Brotherhood.