Kid Colt Outlaw #6

Few westerns dared to mix frontier action with supernatural terror, but Kid Colt Outlaw #6 (1949) does exactly that, promising "The Valley of the Werewolf" right on the cover. The cover by Syd Shores and George Klein puts Kid Colt — red-shirted, hat-wearing, and clearly in trouble — face-to-snapping-jaws with a massive, dark werewolf bearing down on him, while he fires his revolver at point-blank range. It's a striking collision of the Wild West and monster-story dread that makes this early Marvel title genuinely hard to put down before you've even opened the cover.