There actually are some WWG monsters. They are included in the modules.
has Zombies, Centipeeds, Flaming Skeloton, Shadows, Earth elementals, Cryastal/Water elementals and imp and half Fiend.
has Chokers, Gray Render, Some different Humans/Human like devils, Xill, Hell Hounds, Skkeletons, Zombies and a big old Iron Golem.
has Humans, Elves, Faries, Spiders, Ettercap, Dwarves and a Mob.
has Humans, Dogs, Homuncus, Rat, Worms and Vampires
Oh and then there's the Demon, goblins, Worgs and Yeti from , Demon from , and Dwarves in . I thnk a few of the other sets have one off monsters like the Kracken from .
Edit: Oh forgot the Crystal Creatures from the little known megabash.
But I think that gives a pretty good idea of what standees are currently out there.
So there's a few monsters around.
