Vigilantes

Batman is famous for his vigilante behavior. A vigilante is someone who takes the law into their own hands by punishing criminal behavior without going through the legal system because they believe that the government is inefficient or ineffective. Vigilantes often try to evade the law, because their actions, though with good intentions, are considered illegal; They often do not give the criminals due process or a trial. Batman has no supernatural powers; his "superpowers" stem from his wealth. He fights crime with his expensive gadgets and technologically advanced weapons. Vigilante behavior has been depicted in a lot of modern movies and television shows. One good example of a movie is:

In Kick-Ass an ordinary guy decides he wants to be a superhero, but he does not have any superpowers. He tries to be like Batman, but unfortunately he falls short of that, and we see him get stabbed, hit by a car, and end up in the hospital.

Some television shows that show this behavior include:

In Dexter, a crime scene (blood splatter) investigator uses his resources and skills to capture and murder criminals. Dexter is a serial killer, and his victims are people who he believe to be guilty of crimes punishable by death. Though psychopathic, Dexter can be construed as a vigilante.

Examples of evading the law in order to do good for society can be seen in:

One of my all time favorite T.V shows, Supernatural is about two brothers who hunt evil supernatural beings. They often get in trouble with the law because they get accused of crimes committed by the monsters and demons they are fighting. They also engage in illegal behavior, such as breaking and entering, in order to investigate cases. They have to do this in order to save the human race.

Batman is one of the most famous vigilantes, and an impressive superhero, especially since he doesn't actually have any superpowers. As you can see, there are also a lot of other fictional vigilantes worth checking out.
Although be warned, vigilante behavior can appear cool and meaningful, it is not good. It is illegal to go around killing or hurting people, even if they've done bad things. Sometimes vigilantes go too far, or have a messed up moral code, such that they are criminals themselves, and are doing society a disservice. One example is the Klu Klux Klan. They were definitely not superheros, or good for that matter, but are still classified as vigilantes.