When Spider-Man faces Morlun, an enemy who has been sustaining his near-immortality for centuries by feeding on the life energy of people who have totemistic relationships with animals, and when he finally has him on the ropes, it's unclear whether he's about to cross the killing line, but the issue is quickly resolved when Dex, Morlun's Renfield-style cowardly, put-upon assistant, puts a bullet in him and leaves singing "ding dong, the witch is dead."
Skurge, of The Mighty Thor, in one of the most memorable ways possible. He's been treated as a joke by his allies and lover, and ultimately regarded as no more than a dumb brute who occasionally fills in as the Villain of the Week for Thor. Then he snaps. He knocks out Thor before he can make a last stand to let his friends flee Hel, and opts to stand in Thor's place. His reason?
Skurge: They made a fool of me, Balder. They laughed at me. Hela, Mordonna, even the enchantress I love. They all laughed at me. Except you, Balder. Balder is too kind to laugh at Skurge. But whenever they laugh, I hurt inside. Maybe I die a little. Now, I think I am dead already...so I will stay behind and the last laugh will be mine.
His dying words: "Come and get it, demons! 'Tis Skurge's last laugh!" He howls this as shell casings are flying past his face, twin M-16's blazing at a limitless horde of skeletal warriors, and then spends his final moment with a quote that neatly summarizes how badly his 'friends' screwed up by treating him as the easily-swayed muscle of the group.
"And though the Executioner stands alone, and the hordes of Hel seem numberless, not one sets foot on upon the bridge across the River Gjoll."
In the climax of the original twelve-issue maxi-series Amethyst, Princess of Gemworld, the series' Big Bad Dark Opal is literally stabbed in the back by his adopted son Carnelian, whom he had abused in the previous chapters.
Although he survived the attacks, half of Baron Zemo's career was summed up by this trope. You'd think he would've learned after the first few times. He was even attacked by the same abused henchman TWICE.
X-23 does this to the Facility which cloned her from Wolverine to be an assassin. Somewhat subverted that it's actually her biological mother who tells her to rebel and destroy the Facility.
It's very clear Laura is also acting for herself and not just her mother's orders when you consider how she deals with Zander Rice: Sarah Kinney told her to kill him. But when she corners him, she puts up her claws and gives him a truly epic No-Holds-Barred Beatdown. She could have easily killed him instantly, but once she disabled his gun she went after him with her bare hands as payback for everything he did to her. Laura then takes it Up to Eleven when you look at her mission clock and realize she's pounding on him for ten fucking minutes. Capped by Laura's parting Bond One-Liner and Ironic Echo as she leaves him to die:
In the original V for Vendetta (not The Movie), Mr. Almond's wife, Rose, originally securely within the party, but royally screwed over by them after Almond's death, actually kills the fascist despot Big Bad.
V implies that he had somehow planned this since the beginning, stating in the third act that he already had "a special rose" picked out for the head of state.
The film version also had a The Dog Bites Back moment as well. Namely, Creedy, after Adam Sutler made the big mistake of chewing him out, agreed to deliver Sutler to V. In the ending, Sutler is pretty much soiling his pants, so to speak, upon being delivered to V, and Creedy shoots Sutler, only remarking disgust at his fear. Creedy and his men soon join him courtesy of V, who broke his end of the deal.
Subverted near the end of Preacher; Herr Starr's two henchmen try this trope on him after they realize how far gone he is, but he gets the drop on them first.
In The Verse of Preacher, God is a colossal douche and The Grim ReaperWas Once a Man. These two facts are not unrelated, as it turns out God deliberately ruined the Reaper's mortal life so he'd accept the job. It also transpires that God is only omnipotent while He's on His throne. Naturally, the series ends with the heroes tricking Him into leaving it, and the Reaper dishing out a well-deserved reaping.
In G.I. Joe comics, Destro remarks that the Inuit mercenary Kwinn once told him something along these lines: "A man who whips his dogs will one day pull his own sled."
One issue covered a dogfight between Cobra and GI Joe pilots, starting from how they treated their respective mechanics before take-off. You really don't want to alienate the guy whose job it is to make sure your very complicated war-plane is in perfect working order.
The players in Knights of the Dinner Table constantly abuse and exploit the NPC's with whom their characters deal. The inevitable backstab never seems to teach them a lesson.
When Death's Head was hired by a group of rebels to assassinate an oppressive king, he discovers he was actually set up by the King and expected to die in an ambush. Instead, Death's Head proceeds to kill the palace guards and the King — completing the original contract.
The very second Greyshirt story in Tomorrow Stories concerns Sonny, the put-upon caretaker of infamous mob boss "Spats" Katz' apartment building. Forced to turn a blind eye to Spats' actions and weather his constant browbeating and abuse ever since he was a boy, Sonny finally ended it by pushing the wheelchair-bound Spats out of the top floor window — saving Greyshirt's life in the process.
"Nature," an issue of Gotham Central, opens with Officers Munroe and Decarlo beating up Trigger, a corner drug dealer, when he is late with their regular cut. At the end of the issue, Trigger confirms who they are to Poison Ivy right before she kills them.
In Grant Morrison's final issue of X-Men, this trope is used tragically. Jean Grey has triumphantly returned and purged the Big Bad of the sentient bacteria that was making him evil. Just as the former Big Bad appears to be coming to his senses... his abused Igor decapitates him.
Averted in an issue of Sonic Universe - tired of Dr. Eggman's lunacy, Snivley bails on the mad doctor and attempts to squash him once and for all. Instead, Eggman wins and, as a side effect, strengthens his hold on many of his captives.
Snively had better luck in issue 50 of the originalSonicseries. Robotnik had created an "Ultimate Annihilator" that would cause the universe to cease to exist for a billionth of a second, then to spring back into existence, minus Sonic and his friends. Snively seizes the opportunity to be rid of his oppressor and reprograms the machine to annihilate Robotnik instead.
Trachta is by no means a minion, but in Darth Vader and the Ghost Prison 3, we learn that a rogue Jedi Padawan was responsible for his loss of eyes, his loss of limbs, and his being confined to a respirator. When he finds out the rogue Jedi was onboard the Prism and located his cell, his immediate action is to visit the cell and exact revenge by beating the Jedi to a bloody pulp with his cybernetic limbs, even stating that Thom and Vader seal the cell and leave without him, as he's not going to be back for several hours.
In an issue of Cable that dealt with the Balkan Wars, an Albanian scientist shoots his sister for disgracing the family by being raped, and then, a few years later, clones her with all her memories intact (one of what was intended to be an army of clones for the Albanians to use to get revenge on the Macedonians). She, understandably, is pissed at him both for killing her and not allowing her to rest in peace after the worst experience of her life, and once Cable stops the scientists' plan and sends their base crashing down around them, she catches her brother in a back room and stabs the sorry guy to death.
In Welcome To The Jungle, the dog that bites back is a gorilla named Moe that a couple of hags magically compelled to kill someone. Naturally, he's Not Happy when he sees one of the hags threatening one of his zookeeper friends.
In the second arc of the the My Little Pony: Friendship is Magic comics, Spike gets kicked by the Nightmare Forces, and in the end it is he who deals the final blow to destroying the evil force (and releasing Rarity from its control).
During Universe X, it's revealed that the Terrigen Mists ended up transforming Magneto and the Toad, swapping their powers. As a result, Toad makes Erik's life a living hell for all of the hell he put him through.