The Alpha

 General: 

The Alpha is theoretically an Omega class or possibly above level cryptid. The creature would lead the Omega class cryptids into war against humans and cause the next extinction event. It is unknown whether the alpha exists.

 Concept: 

The Alpha was a term coined by Dr. Leonard Brown. The famous cryptozoologist described the Alpha as an explanation of the docile behavior exhibited by the known Omega class creatures.

When researching in 2003, Dr. Brown discovered evidence that the Omega class cryptids may have had a hand in the Permian extinction. He then theorized that the Omega class are simply waiting for the Alpha's instruction and are simply docile as he lies dormant somewhere in the world. Evidence of the events of the Permian extinction as well as research at what the current Omega class creatures are capable of; led Brown to believe that the Alpha must be an incredibly large creature, capable of at least the same destruction of the other Omega class, and that it is probably somewhere under the ground, trapped under shifting plate tectonics.