I have to second this. Sometimes it's just about putting your own spin on what already exists. In our world, the Church calls such creatures Otherkin (the vampires, werewolves, etc) and they are the product of Demonkind. But demons aren't like Christian demons, either; they're a perversion of darkness, which is a natural extension of magick. We also have the Sidhe, and their monsters are those who lose their 'human' qualities by going too far to the extremes of whatever element they represent. So basically, any creature you can think of (minus perhaps Tolkien-esque Elves) will either be Sidhe or human and the monstrous ones will be those who have lost their place in the balance, whether on a light/dark spectrum or on an elemental one.

A banshee, for example, is a water-aspected Sidhe with elements of death magick who lost herself in that death magick (favoring light). A vampire is a human infected by the demons with darkness. A fury is a particularly powerful dark witch who lost him/herself to darkness and rage. A djinn is a Witch who lost him/herself to light, with the type of djinn determined by any elemental magick in the Witch's blood. A sylph is simply a Fae embodiment of air rather than a spirit who lost him/herself to imbalance, a sort of sentient version of that element (the light and dark themselves are already sentient and don't choose to become embodied except when twisted into 'demons' and 'angels'). The Sidhe protect themselves from becoming unbalanced by joining the Seelie or Unseelie courts.

The thing is, even if you create your own creatures, they'll need to be grounded in what we already have here, whether real or mythological creatures. So instead of using existing lore, take what is already out there and just make it your own. That's the key to good writing, really: making it your own.

Also, there are GREAT fantasy generators out there, which might help you come up with names for things.
-Quaddy

Also ember_rain, your world sounds amazingly creative!

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