Such a good question, pinkfloyd.

I think immediately of the burned faces in BLACK PIT OF DR M and WITCH'S MIRROR, MYSTERIES OF BLACK MAGIC's revived corpse, BODY SNATCHER's ape man, SHIP OF MONSTERS aliens. There's much dreck too, of course, but when you consider the conditions and budgets operative back in the 50s/60s, there's much to admire.

Ryan, maybe you thought of this but my guess is that at least some of the people you've listed are conventional makeup and not what we call today "special makeup effects." Some day it would be nice to acknowledge the Pierces & Blaisdells of that time and place. It occurs to me that Guillermo del Toro, who's from Guadalajara, would be in a really good position to research this question (if only he weren't so danged busy with his own trivial activities).... Bueno, Guillermo, ¿que me cuentas?