[quote=Peace Keeper]
Angels, Demons. Ghosts, whatever.
[/quote]

Ghosts, I might allow. As long as they stay 'ghostly' - scary, dark, like to hide in shadowy places. Haunted areas would be abandoned or scarcely visited.
Vampirism and lycanthropy, I will only permit if they affect everyone equally- no race is more vulnerable or resistant to the disease than any other. Also, we'll need to set rules and powers for lycans and and vamps so everyone agrees.
Angels, demons, zombies etc. are not allowed.
Ghouls will have to be 'feral' - normal people who have gone mad through illness, isolation or weird mushrooms. Side effects may include baldness, glowing eyes, unnatural bursts of energy and an aversion to both clothes and any and all other forms of intelligent life.