In the early years (or "Golden Age") of superhero comics, most of the villains heroes encountered were just garden-variety gangsters or, if they did wear a costume, still just human beings at the end of the day. However, that paradigm began to shift with the appearance of clearly IN-human, monstrous characters like Solomon Grundy.
Based on a dreary 19th-century nursery rhyme (was there any other kind?), Grundy was a chalk-skinned zombie who arose from Slaughter Swamp in All-American Comics #61 (1944) to become an arch-enemy of the original Green Lantern and, later on, his Justice Society teammates. True to his undead nature, Grundy remains one of comics' most recognizable and colorful villains well in the 21st century (despite his black & white color scheme).
However, there's a visual aspect of Grundy's earliest appearances that didn't survive into the modern era: his gigantic slab of teeth!
Looking like something between the Japanese caricatures of WWII and celebrity wingnut Gary Busey, Grundy's gigantic chompers were so bizarre and distracting, they nearly canceled out his otherwise imposing presence.
Flash forward to Showcase #55 (1965), Grundy's first appearance in the second (or "Silver") age of superhero comics. Judging from the cover (click to enlarge), Grundy is still sporting some rather large teeth, but nowhere near as slab-like as his 1940's incarnation.
Soon, Grundy would not only lose the goofy teeth but gain considerable bulk as well, in effect becoming a white-skinned version of Marvel's popular Hulk character (right down to the primitive third-person speaking style).