Transformation or other subject matter involving exotic forms are my area of interest, such as:
Feral
Anthro
Nekomimi
Merfolk
Gargoyle
Vampire
Sphinx
Satyr or Centaur
Angelic or Demonic
Cyborg
Digital
Genie or Jinn
Dragon
Mythological (Other)
Cthulic or Otherwise Lovecraftian
Plasma or Liquid or Cloud or other state
Transformations or Otherwise That May Need Specifications Beforehand (to prevent unlawful proliferation):
Final Fantasy Characters
Pokémon
Digimon
Bakugan
Legendz
Blizzard Characters
Spyro
Halo
Naughty Dog Characters
Marvel
DC
Disney
Paramount
Universal
Warner Brothers
Licensed Titles or Copywritten Characters (Other)