In the mid 1950s, DC had a book called Showcase, which was designed to try out new characters. The first three issues had normal heroes like a fireman and a Navy "frogman." They sold terribly, so DC decided to mix things up and try to bring back superheroes. Artist Carmine Infantino was to design a new look for the Flash and he came up with an amazing look that likely made the book a sellout before people even cracked open the front cover! The sleek, lightning-themed red, yellow and white costume would become so popular that it remains one of the few superhero costumes to simply be brought over into television without massive overhauls to the design. It is just that good. There have been tweaks over the years, like altering the logo on the chest or adding lenses to the eyes in the mask, but generally, the costume remains the same today as it did back in 1956.
It’s hard to believe that a hero that's usually shown not even have normal flesh would be known for his sex appeal, but Colossus definitely is. While he’s been a longstanding member of the X-Men, Colossus has always been known for his massive frame and surprisingly skimpy costume. Unlike other “sexy” heroes known for their bad boy qualities, people are drawn to Colossus because he’s generally really sweet and caring, not only with his affection towards Kitty Pryde but also with his sister Illyana. Even with his sweet personality, comic book fans will probably never forget his “centerfolds” from those old swimsuit issues.
For a character who has been such a major part of Batman's comic book history, Catwoman has had a surprisingly unimpressive list of comic book costumes over the years. When she debuted, she was simply dressed in normal clothes, as the name "The Cat" was more general for a thief than anything, and not something that was actually a costume motif. When she then started to reappear as a villain, she went through a few different uninspiring outfits. Then, due to the Comics Code, she stopped appearing in Batman comics period for over a decade.
By the end of the 1940s, superheroes had lost a lot of their appeal to the public. National Comics (now DC Comics) went from having dozens of superhero titles to only having a handful. Most of the members of the Justice Society of America fell out of sight in the world of National. Flash and Green Lantern went from appearing in multiple titles to not appearing in any books at all!