Lone Wolf
The best adventure gamebook series EVER (now available free online as well!) - you get to be a noble Kai Lord fighting the evil Darklords for the future of the realm of Magnamund.  Written by Joe Dever.  Actually contain entire species of new monsters not found anywhere else, e.g. giaks, kraan, gourgaz, zlanbeasts, burrowcrawlers, etc.
Lone Wolf rules!!!!!