I’m making a guess that these are some of the original infernal designs. Celestials have a similar collection of models, however they are all very close to what’s used in the game. These models are quite a bit different than the final versions.

Brute

Brute

Deathmaw

Deathmaw

Felhog

Felhold

Fiend

I can only assume fiends weren’t originally designed to be massed in the way they currently are. Imagine 100 of these guys sprinting around.

Fiend

Flayed Dragon

This design is terrifying.

Flayed Dragon

Gaunt

Gaunt

Hexen

The hexen is named the hag internally, but the design is almost 1:1 the released version

Hexen

Harbinger

Harbinger

Hecubah

This design is also quite different from the final version.

Hecubah

Incarnate

Incarnate

Magmadon

Magmadon

Pit Fiend

Pit Fiend

Shadow Flyer

Shadow Flyer

Shadow Rider

Shadow Rider

Spriggan

Spriggan

Weaver

Weaver

Worker

Worker