Superheroes as a Genre

Superheroes are pretty hard to define as a genre. Pretty much the only way to tell if your story can be categorized as such, is if you have a superhero in it. Though the definition for superhero can be pretty loose depending on who you ask. According to Google a superhero is defined as shown below.
"a benevolent fictional character with superhuman powers, such as Superman."

Wikipedia seems to agree with this, saying that
"A superhero or superheroine is a stock character that possess abilities beyond those of ordinary people, who typically uses their powers to help the world become a better place, or is dedicated to protecting the public, and stopping evil."

In general, the consensus says that you're a superhero if the following criteria are applicable.

• You help or save people
• You have superhuman abilities

A lot of superheroes protect the general public, and, like in many mainstream media, fight villains who set out to destroy the world, the hero, or something else. Most villains want to either destroy the world or take it over. And the hero counteracts by wanting to save people and keep freedom and justice around. It's a balancing act for those who write this kind of superhero story.

Some superheroes are freelance, like Superman, and others work for or with the government, like Captain America. Then there are also vigilantes, and mercenaries, spies, and assassins, and those miscellaneous superpowered characters you see every so often.

The thing is, you don't need a run of the mill superhero to write a superhero story. Megamind is a movie about a villain who ends up becoming a hero because of his own blunders. Deadpool is a mercenary who is just as likely to kill his target as he is the person who hired him, and even himself. Zatanna strives to be the best magician she possibly can, both on and off the stage.

Superheroes can be in fantasy, sci-fi, or even other genres. No two heroes are the same, and who's to say what makes one character more or less of a hero than another? 

Let your ideas run wild!