A vigilante is a member of a self-appointed group of citizens who undertake law enforcement in their community without legal authority, typically because the legal agencies are thought to be inadequate. Occasionally, an individual unassociated with any identifiable group will decide to act covertly as a self-appointed vigilante on behalf of victims who have been denied justice by the courts. A more organized group of vigilantes is called a vigilance committee. The activities of such groups are classed as expressions of vigilantism, condemned as illegal under U.S. federal statute. Notorious examples (not the only ones) include the formation of the Danite Band (1838), the post-Civil War Ku Klux Klan, the frontier feuds and range wars of the 1870s, and the 1875-76 group led by John D. Lee that was directly responsible for the Mountain Meadows Massacre.
Similar but not identical motivations and activities are exemplified by various resistance and insurgent groups defiantly seeking to overthrow established national, regional or local governments, and use reprisals against representatives of immorally oppressive regimes or the entrenched occupation forces of a foreign power, such as the guerilla tactics of the Maccabees against the 2nd century B.C. Syrian tyranny, and the French Resistance of the Maquis during World War II.
In pop culture, the various heroes and villains of the DC Comics and Marvel Comics are vigilantes, who either act alone as solitary individuals or occasionally in cooperative concerted action to overcome a dangerous threat to themselves or others.
Death Wish (film)