Humans in this universe look just like you and me.

The most populous and technologically advanced out of all the groups and the most dominant on the land.

Most of them are sceptical, or even oblivious to the existence of the other races.

Underwater beings with the tail of a fish and the upper body of a human.

Not only they have gills, but lungs too! The average merfolk doesn't go anywhere near the surface to breathe, though, ever.

Stuck in early Byzantine period culturally-wise.

Highly intelligent and strong sea monsters.

They like riddles,tricking humans and the taste of raw flesh.

They can live for up to 5000 years! There is only a small population of them left though,so they don't pose much of a threat.