I know there was a list put together for the magi listed in the various books. But has anyone put a list together for all the various creatures that have appeared in the additional books?
Not that I know of. I considered doing this, but other efforts have met little use and I've had a general lack of enthusiasm.
Fine idea, though, and you may find it useful for yourself, and others may as well.
There is a list here
redcap.org/page/Creature_index
I don't know how complete it is (it probably isn't very...), and it sure could be useful to give a few more details here and there.