Which actor sprites do you think came first?

When Carmack was designing the monsters for Doom, which one do you think was the very first actor model to be made? Things like the Cyberdemon, Spider Mastermind, and lost soul sprites didn't appear until the final game. The pinky demon sprites seem to have some frankensprited parts from the hell baron (you can see the baron of hell's back on the pinky demon's forehead) which would indicate that it was made after the Baron of Hell. The zombiemen are modeled after the player sprite which indicates they came after the player. The player and Baron of Hell were made from digitized photographs of clay models, while the imp and Cacodemon were presumably drawn from scratch. Which of those four models do you think was made first before anything else? 

My best guess: The Baron, the Pinky Demon, then the Imp. That's the order they're found in the Doom Alpha 0.2,, and that supports the 'Baron's back on Pinky's forehead' thing. Pinky's sort of bizarre looking, with cleaner teeth, and a weird looking slide/walk. And Imp has orange eyes and mouth, due to a somewhat different colormap, with an incomplete first row, and the red range (192 thru 207) replaced with orange. It's actually very cool looking:

I like that Imp, I also like the Pinky's cleaner teeth and different looking eyes, actually looks more menacing than the final design.

Considering what I've managed to see from it's early stages I'd say it was either the Imp, The Baron, or the Pinkies, and everything else made it much later.

Since you mentioned Lost Souls, not sure whether they appeared only when the game was nearing it's completion, as they also went through a complete redesign. For sure that they weren't among the first though.

I have nothing to go on this, but I have a gut feeling that the baron was made first.

The imp is the simplest, however, would've been the easiest to make, assuming the following isn't true. I seem to recall reading somewhere that they just posed the player model like the imp and heavily edited it in post, no idea where I read that or how accurate it may be.

 Adrian Carmack made a lot of concept art for the baron, some of which was adapted into game textures, but I don't recall ever seeing concept art for the imp.

I'm going to make a wild guess that the baron was originally supposed to be the imp (would fit with the swarm of baron-like creatures on the title screen), but then they thought a less imposing sprite would be better for the basic mook and they imp-rovised a replacement. Plus originally the pinkies were supposed to be demon sergeants, and you can't imagine a pinky bossing over a baron.