Revenge (also vengeance, retribution, or vendetta amongst others) consists primarily of retaliation against a person or group in response to a real or perceived wrongdoing. Although many aspects of revenge resemble or echo the concept of justice, revenge usually has a more injurious than harmonious goal. Whereas justice generally implies actions undertaken and supported by a judicial system or ethical majority, revenge generally implies actions undertaken by an individual or narrowly defined group outside the boundaries of judicial or ethical conduct. The goal of revenge usually consists of forcing the perceived wrongdoer to suffer the same pain that was originally inflicted or worst than the original
In some societies, it is believed that the punishment in revenge should be more than the original injury, as a punitive measure. The Old Testament philosophy of "an eye for an eye" (cf. Exodus 21:24) tried to moderate the allowed damage, in order to avoid a vendetta or series of violent acts that could spiral out of control—instead of 'tenfold' vengeance, there would be a simple 'equality of suffering'. Detractors argue that revenge is a simple logical fallacy, of the same design as "two wrongs make a right." Some Christians interpret Paul's "Vengeance is mine; I will repay, saith the Lord" (Romans 12:19, King James Version) to mean that only God has the moral right to exact revenge. On the other hand, in Romans 13, Paul dignifies the Roman emperor and his military governors as licit avengers on behalf of God: "he (the prince/magistrate/policeman) beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil". Every major religious system contains some method for the mediation of disputes and for the limitation of vengeance by imputing a sense of cosmic justice to replace the often faulty justice systems of the human world.
Of the psychological, moral, and cultural foundation for revenge, philosopher Martha Nussbaum has written: "The primitive sense of the just—remarkably constant from several ancient cultures to modern institutions…—starts from the notion that a human life…is a vulnerable thing, a thing that can be invaded, wounded, violated by another's act in many ways. For this penetration, the only remedy that seems appropriate is a counter invasion, equally deliberate, equally grave. And to right the balance truly, the retribution must be exactly, strictly proportional to the original encroachment. It differs from the original act only in the sequence of time and in the fact that it is response rather than original act—a fact frequently obscured if there is a long sequence of acts and counteracts" .
Vendettas or "blood feuds" are cycles of provocation and retaliation, fuelled by a burning desire for revenge and carried out over long period of time by familial or tribal groups; they were an important part of many pre-industrial societies, especially in the Mediterranean region, and still persist in some areas. During the Middle Ages, most would not regard an insult or injury as settled until it was avenged, or, at the least, paid for — hence, the extensive Anglo-Saxon system of "wergild" (literally, "man-price") payments, which placed a certain monetary value upon certain acts of violence in an attempt to limit the spiral of revenge by codifying the responsibility of a malefactor. The story of Wimund the Bishop illustrates the typical implacability of the time: its hero, though blinded and imprisoned, would avenge himself against his enemies "if he had even but the eye of a sparrow".
In Japan's feudal past, the Samurai class upheld the honor of their family, clan, or their lord through the practice of revenge killings, or "katakiuchi". These killings could also involve the relatives of an offender. Today, katakiuchi is most often pursued by peaceful means, but revenge remains an important part of Japanese culture.
The goal of some legal systems is limited to "just" revenge — in the fashion of the contrapasso punishments awaiting those consigned to Dante's Inferno, some have attempted to turn the crime against the criminal, in clever and often gruesome ways.
Modern Western legal systems usually state as their goal the reform or re-education of a convicted criminal. Even in these systems, however, society is conceived of as the victim of a criminal's actions, and the notion of vengeance for such acts is an important part of the concept of justice — a criminal "pays his debt to society" evinced by countries such as the United States continuing the practice of capital punishment.
Interestingly, psychologists have found that the thwarted psychological expectation of revenge may lead to issues of victimhood.
The first written appearance of the proverb "revenge is a dish best served cold" is often credited to the 18th century novel Les liaisons dangereuses, but since it doesn't actually appear in the original French language text, the validity of this attribution is unclear. The English version of this phrase in that exact wording can be attributed to The Godfather by Mario Puzo, a major bestseller in 1969. However, the phrase appeared in the 1949 film Kind Hearts and Coronets as "revenge is a dish which people of taste prefer to eat cold. The more well-known wording of this quote is also featured in the title sequence of the Quentin Tarantino film Kill Bill: Vol 1, accredited as an "Old Klingon Proverb", referencing the phrase's usage in Star Trek II: The Wrath of Khan, where it is similarly cited as such. It means that to be successful, revenge should be a considered and planned response enacted when the time is right, rather than a hasty and 'hot-blooded' action which will increase the chances of failure.
Revenge is also a prominent theme in contemporary motion pictures; e.g., Revenge, The Punisher, V for Vendetta, Sweeney Todd: The Demon Barber of Fleet Street, Kill Bill, or Park Chan-wook's Vengeance trilogy are archetypal artistic portrayals of revenge. Revenge is also portrayed in the motion picture, Prom Night (both 1980 and 2008 versions where a sadistic killer gets vengeance for his sister's murder, as do Friday the 13th, A Nightmare on Elm Street and Terror Train.
Other movies deal with this concept in a more fantastic or futuristic setting, such as Star Trek II: The Wrath of Khan, where Khan's hatred of Kirk and his desire for revenge would became so intense that Khan would lose everything, even his own life in his efforts for revenge. This intense desire to obtain revenge above all else can be witnessed in Khan's dialogue, paraphrasing Captain Ahab:
"He tasks me! He tasks me! And I shall have him. I'll chase him round the moons of Nibia and round the Antares maelstrom and round perdition's flames before I give him up!"