Have any of these ever been done?
Dr Strange - the Ancient One
From Thor #141 - Replicus
Sub - Mariner - The Faceless Ones (I think there's a similar group with Dr Strange as well)
The Martians from the Killraven series
The Badoon!
The Royalist Forces of America - Captain America #196
The Deviants from the Eternals.
The Jupiter men from the first Thor story
Namor's Atlantean soldiers
CB has done some wonderful Atlanteans from both companies.
I've got something I'm using for the Badoon in Marvel Adventures, but I don't remember how accurate they are.
A few thoughts on my requests. Looking at the classic Silver Age Badoon, they look a lot some classic fantasy goblins. Maybe importing some and reskinning them would work, giving them some modern weapons, etc.
The Jupiter men - I think there's a Impossible Man mesh out with a pointed head. Maybe it could be stretched a bit if needed and a modded 'Thing' skin added. Or any normal mesh could have it's head stretched out.
Benton - found the Atlanteans - I think that the one set was actually imported in by me back in the day from MUA and I had forgotten.