In modern terms, a vigilante is anyone who takes the law into their own hands. Vigilantes often operate in secret. The term vigilante stems from the name "Vigiles Urbani" given to the nightwatchmen of Ancient Rome who were tasked with fighting fires and keeping a lookout for runaway slaves and burglars.
In the United States vigilantism was especially strong in Montana during the days of the gold rush and in California during the struggle for control of the gold fields after the gold rush of 1849 and during labor unrest between the World Wars. However vigilantism frequently broke out in other areas of the country and often resulted in Lynching of suspected criminals. Not all activities were spontaneous; nineteenth century America had several well-organized vigilance committees.
In Spanish, vigilante means 'watchman', which is how many of these groups started, where there was no organized law enforcement.
Vigilantism is also the basic concept from which many contemporary fictions are derived, including stories published in dime novels and comic books. Many of the heroes of pulp fiction, such as Doc Savage and The Shadow, and Comic book superheroes, such as Batman, Daredevil, and Spider-Man, are considered to be vigilantes due to their actions being self-motivated, and generally aimed at a good result, rather than being duly-appointed officers of the law. The extreme of the vigilante-type superhero is Marvel Comics' character The Punisher, who used flagrantly illegal methods such as mass murder and torture to fight criminals, while second up being Daredevil who after the Frank Miller age, began killing certain enemies in cold blood.
In the modern-day western world, vigilantism often occurs when the local population is frustrated with the complex and time-wasting and seemingly unfair court procedures and rulings that apparently allow felons to walk free or be found not guilty. Vigilante "justice" often takes the form of assault, arson, and possibly even death of the accused person. At times, certain criminals will opt to forgo Parole for fear of receiving vigilante justice when they were released.
Vigilantes have a reputation for 'bringing justice' to the wrong person. They usually act without conclusive evidence, and when they act they don't go at length in determining the identity of their target. They often harm innocent people accidentally, such as killing a passerby in a shootout; or because they are in some way related to the people they want to punish. They also tend to punish disproportinately harshly, such as killing a shoplifter. Examples of vigilantes like these have been featured in the Marvel comic The Punisher, specifically the characters Mr. Payback, Elite and The Holy, who featured prominently in the Welcome Back, Frank mini-series, which was written by Garth Ennis and Steve Dillon, the creators of the popular Vertigo series Preacher. Real life examples of these can be seen at the bottom of the article.
Nowadays vigilantism not only occurs on the streets but also in schools. As a result of bullying and authority figures who fail to enforce the rules, angered students often find in vigilantism a violent way to restore the missing order.