Ok, technically this is a Silver Age tale, but we can bend the rules occasionally. And anyway, if you can't read at Halloween the creepiest, flesh-crawlingest horror comic ever done ever, when can you?
The Monster Of Dread End appeared in Dell's Ghost Stories in 1962, was written by John Stanley and illustrated by Ed Robbins, and seems to come from Hell itself. No matter how many times I read it, it still scares the living crap out of me. You can look at it all logically, and say it's kind of Lovecraftian. You can say the fact that the creature appears to be dead but obviously isn't, or the fact that you never see all of it ( or do you? ), or even the fact that there's no explanation for it all adds to it's terror. But I think it's more than that. Somehow, Stanley & Robbins tapped into something primal on this story. Maybe it's the childhood fear of things under the bed or in the wardrode, I don't know, but in some way I'm not able to intellectualize, The Monster Of Dread End creeps me out like nothing else. See if it does the same to you...
The Psycho Lover (1970)
11 hours ago