Undead level advancement

So a fascinating concept I saw posted on another blog, as well as presented in some GameLit of Japanese origin like Overlord and Tensei Slime, is the idea that the undead monsters are actually a hierarchy along which an individual monster evolves as its hit dice or challenge rating increases. (This can be applied to monsters in general, but that's another tangent.) I briefly touched on this in one of my previous undead taxonomy posts, but the "undead progression road map" expands this immensely beyond my own suggestions. For example, it posits the progression: ghoul → wight → vampire, as seen in the image below.

I don't know if I said so already, but I am definitely using ideas like this in my own world building!