Li Shenron
Legend
I am not a fan of ugly stuff like oozes and most aberrations, but neverthless I have indeed used some of them (usually because they were in published adventures).
There is actually a lot of creatures from 3ed MM which I haven't used yet, but the reason is basically that I haven't yet DMed enough
and also I haven't DMed very high-levels campaigns. Some very high CR creatures (titans, elder dragons) have appeared in my setting, but not in combat against the PC!
Just to name a few of the ones which never had a spot in my campaigns and probably will never have:
Aboleth
Aranea
Delver
Devourer
Digester
Kraken
Locathah
Phantom Fungus
Phasm
Skum
Spider Eater
Thoqqua
Tojanida
Vargouille
Some because they are lame, some others because I just don't get the sense of them. Many are acquatic ones which makes them more difficult to use. Finally I think doppelgangers already cover the shapeshifting role and I don't need more.
There is actually a lot of creatures from 3ed MM which I haven't used yet, but the reason is basically that I haven't yet DMed enough

Just to name a few of the ones which never had a spot in my campaigns and probably will never have:
Aboleth
Aranea
Delver
Devourer
Digester
Kraken
Locathah
Phantom Fungus
Phasm
Skum
Spider Eater
Thoqqua
Tojanida
Vargouille
Some because they are lame, some others because I just don't get the sense of them. Many are acquatic ones which makes them more difficult to use. Finally I think doppelgangers already cover the shapeshifting role and I don't need more.