Hello! I was thinking about doing an adventure that features a gallery of extinct creatures. It would be filled with beholders, displacer beasts, grell, mind flayers, umber hulks, etc. I'm not sure what all didn't transfer to Pathfinder though. Does anyone have a complete list of old D&D monsters that weren't in the ogl?
They are named on this site. You will have to do a search. I can tell you that the yuan-ti, umber hulk, gith (both races), displacer beast, mindflayer, and beholder are not ogl sanctioned.
Took a bit of searching but I think I found it. It seems to include…
beholder, gauth, carrion crawler, tanar’ri, baatezu, displacer beast, githyanki, githzerai, mind flayer, illithid, umber hulk, yuan-ti.
So I guess Piazo could actually use the grell after all. ^_^