When you think about it, most people are probably pretty unfamiliar with the vast majority of comic books or graphic novels. If it weren't for a number of the movies and television shows out there, characters like Iron Man, Doctor Strange or Green Arrow would probably draw something of a blank expression from the average person if they were asked about them.
With the possible exception of the Teenage Mutant Ninja Turtles, the likelihood of this further increases when you go beyond the industry's titans in Marvel and DC. Mention Usagi Yojimbo and somebody may look at you like you've lost your mind. You might say 'Savage Dragon' and they'd probably be like 'Savage Who?'
But there have still been many lesser-known comic books to get their shot at the big screen, to varying degrees of success. Often times it can be the non-superhero stories that can give a small publishing company its best chance at seeing one of their stories come to life.
While Marvel and DC have long set the standard, there is still plenty of room for less famous titles to make their mark.