By definition, a hero is a remarkably brave person, somebody admired, a man with superhuman powers, or a long sandwich. Since this is not about food, you can rule out the long sandwich definition. But why does a hero have to be some one is extraordinarily brave or an admired by the masses? Adolf Hitler was admired by people, so does that qualify him as a hero?
What remarkably brave thing must a person do to be a hero in someone else's eyes? Why does saving another person's life or going to war make a person brave? Is not it our duty as human beings to do these things, without question or thought? A person should not be called a hero because they do something they should do, but because they do something, no one else will do. People who will stand-alone in the midst of millions because they believe what they think is right should be called a hero. Yet, people are shunned because they think differently.
Since Superman has superhuman powers, he is apparently a hero. Yet, Superman is character in a comic book created by two men, Joe Shuster and Jerry Siegel. These two men should be the ones being recognized as heroes, not the person they created. They are the ones who created Superman and by doing so affecting the American culture, yet in time their names could be forgotten. If you call Superman a hero, do so because he affected the culture of the world, not because he can fly and is bulletproof.
There have been millions of heroes, yet society only recognizes a few. Does that imply that unless your name ends up in a history book, you are not, or never will be a hero? Hundreds of people have made the world what it is today, however, we do not acknowledge their impact on the world, or even their names.

Anyone could be a hero, everyone has a hero, and everyone is a hero to someone. Maybe we call people heroes because of what they can do. We admire them because they do or did something we cannot do, or are to afraid to do ourselves. You can be a hero to a little child simply because you can rub your tummy and pat your head at the same time.
Maybe it is not only beauty in the eye of the beholder, but bravery, admiration, and heroism.