This is a tough one. Considering how many loopholes you could conceivably open to powergaming and godmoding with just about any offshoot of mythos. The only thing that's completely disallowed is Aliens. But most of you knew that. Here's the list so far:
Angels, Demons, Archangels, Demigods, satan, god, and wizards. That's in with the 'wizard' setting, not actual wizards with wands and stuff. These go without saying as this is the realm of your headwiz and all the staff.
Ghosts and Spirits also inhabit this realm and can flow freely from one place to another without any ties. The dead are allowed to remain dead as long as they haunt someone in the IC world on a regular basis and stay out of the wizard's areas. Those that are Ghosts and Spirits have the option of being 'reborn' into another life with or without remembering the previous and interim time. They also have the option of being created Vampires or Zombies if their history calls for it. Or if they begged god/satan to give them eternal life by sucking the life out of someone else. You know, there's a bit of leeway here. But if we catch you godmodding or powergaming with what you're given, you're back to ghost again. ;)
Please note that Vampires and Zombies are NOT allowed into the Eternal Realms once created because of their nature.
Modern (1950's) Realm
Humans (the ubiquitous constant)
Zombies - As in undead in old horror movies or partially dead from voodoo.
Light Psychics - As in gypsies or fakirs of any allowable race. Not jedis.
Cyborgs - As in the movie Metropolis or partially so. Stylized 50's.
Furries - As in the Island of Dr. Moreau (Not Moeru, he'll eat you).
Meta-Humans - As in SCIENCE! Because Michael wills it so.
Vampires - Historical. Modern Vampires can NOT be nobility unless varifiably elvish or partially elvish.
Werebeasts - With non-mythical animals ONRY.
Pokemon/Digimon and Pokemon/Digimon Morphics - Created by science in laboratories to please the rich. These must be pre-approved!!
The Blob - Coming to a theater near you! Slowly.
Medieval Magical Realm
Humans (they're everywhere, aren't they?)
Meta-Humans - Created by elder races ONRY. A pixie or druid healer, perhaps.
Elder Races - Elves, Pixies, Faeries, Orcs, Gigas, Dwarves, Gnomes, etc. Those wanting Nobility must be pre-approved.
Elves align with good and evil, Pixies align with elements, Faeries align with seasons, Dryads align with Trees, Hamadryads align with bodies of water. If there is any question of where the power of an elder race lies, please see god (the headwiz).
Sentient Animals - As in Salem, Sabrina's cat. These may be magical beasts as well.
Mythical Animals - Dragons, Unicorns, Griffons, etc. These must be pre-approved.
Vampires - Of the older variety. Those wanting Nobility must be elvish as well.
Werebeasts - Including mythical animals.
Mythical Furries - Sort of like werebeasts that can't turn human or true animal.
Changes will come as necessary. :)