I often wished there had been a Fallout-like game for Fantasy.
People say there was, but it never became such a popular milestone.
 
To me, it depends on what counts as a CRPG. It would probably be Pool of Radiance, back when it was all colored pixels and shapes.
 
Curse of the Azure Bonds on the C64. The game still contains some of the best and most memorable encounters I've seen in a D&D game and indeed cRPG in general.