Never underestimate the importance of well made iconography. Sometimes the simplest images and symbols will tell your audience more about the character or organization they're associated with than any amount of dialogue or conflict could. And one type of story that has always understood this is the superhero comic.
From the first superhero all the way to modern era, superheroes have always had some kind of trademark symbol or visual detail that readers can immediately place as belonging to them and only them. There might be imitations or subversions, but there's only one original, and everyone knows it.
But, of course, some are more famous than others. Some are so iconic, so immediately recognizable, that you don't need any clarification on whom it belongs to when you see it. These superhero symbols have maintained the core idea of their character throughout because of how integral a part it is to the concept of the hero wearing them.
Whether because of how they reflect their beliefs and character, or because it's just that damn good a design, these are the ten most iconic superhero symbols out there.