Can you think of a story or movie where the system fails the common man and he (or she) must seek justice outside of the law? I can.
There are numerous movies that explore this basic plot. For example: the Dirty Harry moives with Clint Eastwood or the Death Wish movies with Charles Bronson (yes, I'm showing my age with these referances). A more recent example, A Law Abiding Citizen with Gerard Butler. And of course, we have a gambit of superhero moives and comic books to choose from such as the enitre Batman franchise or the Punisher or the CW's TV show - The Arrow.
The Reaper series is my take on the modern day masked vigilante.