Revenge

Revenge is the act of taking retribution upon another being for something that being has done to them.

Overview
Revenge is often sought for a multitude of reasons. Some vary from pranks between friends or siblings to a terrible act such as the death of a family member or friend. Many hunters often get into the life because of a need for revenge on a monster or demon. Vengeful Spirits are ghosts whose whole reason for being is to seek revenge against those who have wronged them or, in some cases, on the same type of person as those who have harmed them.

Primordial Entities

 * The Darkness - Described as "the oldest grudge," the Darkness sought to gain revenge against her brother God for locking her away for eons in order to make Creation and was willing to destroy the Universe to achieve it. After mortally wounding God, the Darkness began to feel remorse for her actions as she never wanted her brother dead. The Darkness was ultimately convinced to reconcile with God and she healed the injuries she inflicted upon her brother before they left the Earth together to reconcile fully.

Demons

 * Jael - A sadistic Crossroad Demon that was exorcised by legendary hunter Asa Fox and thereafter sought revenge upon him for decades. Following Asa's accidental death at the hands of his best friend Bucky Sims, Jael began attempting to get revenge on Bucky instead as he felt Asa was his alone to kill. After killing several hunters at Asa's wake and revealing the truth of Asa's death, Jael was exorcised once more by Sam and Dean Winchester, Max and Alicia Banes and Mary Winchester in sequence.
 * Abaddon Loyalist - Following the death of the Knight of Hell Abaddon, this demon, an Abaddon loyalist, attempted to gain revenge upon Dean. However, Dean, now a Knight of Hell himself, easily killed the demon with the First Blade.
 * Lucifer Loyalists - Following the defeat of Lucifer whom they served, these demons joined Meg in her efforts to gain revenge upon Crowley. However, one was killed by Sam Winchester when he realized that the demon was more interested in killing the Winchesters than taking on Crowley and the other two were killed by Crowley's Hellhound Pack.
 * Meg - After being exorcised by the Winchesters during the Attack at Bobby's House, Meg began seeking revenge upon them upon her return from Hell. To gain her revenge, Meg possessed Sam and used him to target and kill other hunters while simultaneously attempting to convince Dean that Sam had gone evil and Dean needed to kill him. During a fight in Bobby's house, the Demonic Binding Link keeping Meg in Sam's body was broken by Bobby Singer, forcing Meg to flee Sam's body and end her revenge plot.
 * Meg - Following the defeat of Lucifer, Meg, a Lucifer loyalist, developed a grudge against Crowley, the new King of Hell that had aided in Lucifer's defeat. In order to gain her revenge, Meg formed a reluctant alliance with Sam and Dean Winchester to raid Crowley's Monster Prison, retrieve Sam's soul and kill Crowley. After failing to retrieve Sam's soul, Crowley was apparently killed when Castiel burned Crowley's bones. A year later, with Crowley still alive, Meg formed an alliance with the Winchesters to protect the memory-less and then insane Castiel from Crowley and to defeat the Leviathans. After being rescued from Crowley's demons, Meg aided the Winchesters in the Hunt for the Angel Tablet and sacrificed herself so that they could escape, being killed by Crowley in the process.
 * Drew Neely - Following the death of the Knight of Hell Abaddon, Drew, an Abaddon loyalist, attempted to gain revenge upon Dean. However, Dean, now a Knight of Hell himself, easily killed Drew with the First Blade.
 * Ramiel - On a mission for the British Men of Letters, Mary stole the Colt from the Prince of Hell Ramiel, not knowing who the demon actually was or letting her companions know the true nature of the mission. Enraged at the theft from him, Ramiel chased the Winchesters and the mortally wounded Castiel with the intention of retrieving the Colt and killing them. Despite the intervention of the King of Hell Crowley, Ramiel was not deterred and once the Winchesters failed to return his property, attacked. In the fight that followed, Ramiel was killed by Sam Winchester with the Lance of Michael and Castiel's life was saved when Crowley broke the Lance and its power over Castiel.

Monsters

 * Richard Beesome - After Alex fed him to her vampire "family," Richard became a vampire himself and killed his own family in his bloodlust. With the help of Henry, Richard attempted to gain revenge against Alex by building her life up and then destroying it. His revenge was foiled by the Winchesters and Richard was killed by Dean Winchester.
 * Roy Dobbs - After being used as bait for the Female Arachne by a soulless Sam Winchester, Roy was turned into an Arachne himself and became consumed by a desire for revenge against Sam. After luring Sam, now with a soul and no memories, back to town, Roy attempted to kill Dean to get at Sam. However, his wife freed Sam who was able to kill Roy and save his brother.
 * Elias Finch - In 1861, the wife of phoenix Elias Finch was raped and murdered by a local deputy, a crime Elias was framed for by the local judge, sheriff and the deputy. Elias survived his execution due to his nature as a phoenix and sought revenge against those who killed his wife and framed him. Despite the intervention of the Winchesters, Elias succeeded before he was killed by Dean Winchester with the Colt.
 * Henry - High school student turned into a vampire by Richard Beesome to aid his revenge against Alex. The plot was foiled by the Winchesters and Henry was killed by Claire Novak.
 * Benny Lafitte - Following his resurrection by Dean Winchester, Benny sought revenge upon the vampirates who had killed him and The Old Man in particular. With the help of Dean Winchester, Benny wiped out the vampirates.
 * Alpha Vampire - After the British Men of Letters began an operation to wipe out all vampires in the United States, the Alpha Vampire led a vampire raid on the British Men of Letters compound to wipe out the British operation and protect his children. Though the raid succeeded in killing most of the operatives present, the Alpha Vampire was killed by Sam Winchester with the Colt and help from Mary Winchester and Mick Davies, driving off the surviving vampires.