Well, the “generic” types are always good, both male/female (each character “pack” should include both genders):
- Orc
- Ogre
- “Various demonic creatures” such as succubi, hellhounds, etc…
- DRAGONS!
- Giants
- Ghosts: basically re-skinned of other types
- Skeletons
- Zombies: We already have zombie models, but the clothing textures are modern day
- Giant insects: Spiders, Ants, Wasps, Scorpions, etc…
- Giant Bats / Bat swarms
- Gnomes
- Gnolls
- Various giant reptiles: Snakes, Crocodiles, Basilisks, Adamantoise, etc…
- Griffons
- Centaurs
A couple of good lists for “generic” types:
http://gamedesign.wikidot.com/rpgdesign:monsters
Alot of “creatures” can be re-skinned, so it would be wise to do a “base mesh” characters (and include the UVW Template), and then you could also sell “texture and motion packs” to make them into other various types of characters.