In American Vampire, Chase Hamilton lures Pearl Jones to her death and feeds her to a coven of vampires. When they meet again after Pearl is revived, he gives no indication that he remembers even meeting her.
In a later issue, Vampire Hunter Travis Kidd confronts SkinnerSweet and accuses him of murdering his parents, to which Skinner responds; "Could you narrow it down a little? [...] On second thought, I don't really give a shit!" As it turns out, Skinner didn't actually do it - they were killed by a different group of vampires, but Travis blames him anyway since they only came to the area to hunt Skinner down.
When Aubrey Jason is confronted by Charles and Royal Williams, he readily admits he doesn't remember — nor care about — his cold-blooded murder of their parents twenty years ago.
In a rare example of this being on the heroic end, the First Family has this relationship with one alien civilization. The aliens consider the Fursts to be the greatest monsters in their history, and dedicate a significant chunk of their entire culture and ideology to avenging the death of their beloved prince. Meanwhile, the Fursts clearly consider them to be just another of their many opponents.
The Authority: Kev opens with SAS commando Kev Hawkins being cornered on the toilet by two men intent on killing him. They're IRA terrorists out for revenge, because Kev killed their comrades and brothers during an incident in west Belfast. Kev hasn't the faintest recollection of this mission, and doesn't even recognize his assailants' faces. He even uses "Sorry, mate. Still don't remember" as a Pre-Mortem One-Liner.
In Protoplasman by Big Bang Comics, the hero-to-be confronts the villain, declaring that the villain killed his brother. (It would soon turn out that he wasn't dead, just kidnapped. And shrunk, because why not.) The villain's response: "I've killed thousands of people! You can't expect me to remember them all!"
This trope is Mother's Milk's motivation. He and his brother Michael suffered non-beneficial mutations from Compound-V that had been deliberately introduced into their mother's workplace, leading their father to sue Vought-American for damages. The lawsuit takes a massive toll on his father, but eventually, they manage to win a suit with Vought's deck stacked heavily against them. The victory is rendered hollow for MM however, when he overhears Vought's lawyers cheerfully brush off the case which crippled him and his brother and nearly killed his father due to stress as "You win some, you lose some." He realized from this that there was simply nothing he could do while staying above board to actually hurt the people who ruined his life.
Hughie is motivated to join the team when his girlfriend was turned into collateral damage by speedster superhero A-Train, who, at the time, barely even stuck around to apologize. When he actively confronts A-Train about it, he's seemingly forgotten all about it.
Diabolik has killed so many people he cannot possibly remember them all, or even most of them. At least one, the daughter of a random cop who was ran over by Diabolik simply because he found himself in his way, admits he most likely has no idea who's the person she wants revenge for, something Diabolik calmly confirms. It's implied Diabolik will remember her for having forced him to actually try to kill her when she tried to get her revenge.
In the 500th issue of Doctor Who Magazine, the Twelfth Doctor asks Josiah Dogbolter if he remembers Gus Goodman, a companion from the 1980s comics who died as a result of his actions. Dogbolter has no idea who he's talking about. "Do you know how many nobodies I've killed to get where I am today?" Unfortunately for him, this is then recorded and broadcast for all to see.
In Terry Moore's Echo, NSB agent Ivy Raven is confronted by the remains of Hong Liu, one of the villains she shot and nearly killed earlier in the same story, and when he begins raging at her, she tells him "I've burned so many psychos, kinda hard to tell you guys apart."
Inverted by Melaka Fray in Joss Whedon's comic Fray. When Mel was a little girl, she and her fraternal twin brother Harth were attacked by the powerful vampire Icarus. Harth was killed, and only by luck did she survive. Since then she's dreamed of revenge, but when she encounters Icarus again and he not only knows her, recognizes her despite being a grownup now, and is aware that she's the Slayer, (something Mel only just learned about) she takes that as a sign that something weird is going on. As she says, she and Harth should have been nothing to Icarus, just another victim in a lifetime full of them and forgotten by the next day. Sure enough, Harth was turned into an Undead Child and has become the Big Bad, while Icarus is his dragon.
Another heroic example, in the Hellboy short story "Act of Mercy", Hellboy is summoned by Dyavo Mahr for a rematch having defeating him once before. Dyavo carries on about their battle being one of legends, but Hellboy doesn't recognise him and dismisses him because of how weak and powerless he is. Eventually Hellboy sees what Dyavo really wanted from their second encounter having fallen so far from what he used to be, states that he is too much of a threat to live, and puts him out of his misery
Invoked: Dredd is held at gunpoint by a woman whose husband he once arrested, but he tells her that he arrests a lot of people and can't be expected to remember them all. However, it turns out that he does remember, and he was just playing for time.
This trope was played for real when Whitey, the first perp we get to see Dredd arrest in the comics, escapes from captivity in the 10th Anniversary story with nothing but a grudge against Dredd on his mind. However, Dredd has no recollection of the man at all.
"Who the hell was Whitey?"
And in a similar later story, Bert Dubinski, the very first guy Dredd arrested back when he was still in training, is released from prison after thirty-five years and seeks Dredd out, believing he must have some significance to the lawman. He does not respond well to finding out Dredd regards him as just another criminal.
In the Mark Millar series King of Spies, British superspy Roland King tangled with a brother-sister team of assassins in Panama in 1990. He left the pair for dead but 30 years later, it turns out they lived, albeit her with no arms and him with no legs. They go after King in a wild fight, each howling how they've waited decades for their revenge. King's reaction is to muse on how he doesn't even recognize these two and reflects on how many lives he ruined without remembering them.
Another heroic example happens in the Nikolai Dante story "The Memoirs of Nikolai Dante". After Nikolai finishes telling Odessa his life story, a guy with a gun bursts in, ranting about how Nikolai ruined his life. Nikolai is at first nonplussed, and when the guy explains that Nikolai killed his comrades and ran off with his girlfriend, Nikolai responds that that sounds like the sort of thing he would do, but the guy would need to be more specific.
Red Ears: A lothario who has an affair with a married woman every other day receives a letter from a man telling him to stay away from his wife or he'll kill him. When one of his friends offers the simple solution of just complying with the demand, the guy notes that the letter isn't signed.
One Red Sonja comic had this: A mighty warlord is after Red Sonja because her troops fought off his several years ago, and she personally cost him his left eye. (How he pulled through after that wound...) When they meet in a duel because of a city she's defending, he's furious when she tells him she doesn't remember him at all. She says this twice. And he cheats to win the duel.
From Star Wars (Marvel 2015), depicting a pre-The Empire Strikes Back confrontation between Luke Skywalker and Darth Vader, the latter having no idea of Luke's identity or their blood relationship.
Vader: Wait... This lightsaber... I know this weapon. This once belonged to— [Imperial Walker stomps through roof]
Darth Vader: Dark Lord of the Sith: In a heroic example, the Grand Inquisitor has spent years fuming over how Chief Librarian Jocasta Nu refused to allow him to access forbidden knowledge in the Jedi Archives. Confronted about this, Jocasta doesn't remember him and makes it clear that he was just one of a large number of Jedi with similar requests that she had denied over the years.
Becomes a major plot point in the comic story Jabba the Hutt: The Gaar Suppoon Hit. First, Jabba made a (phony) bomb threat against his rival Gaar Suppoon's palace, knowing that this would cause Gaar to hire Imperial bomb specialist Kosh Kurp to come to the palace to inspect it for bombs. Then, while attending a business ceremony at Gaar's table, he reveals in front of Kosh that Gaar had once gone by the false name of "Sonopo Bomoor". This causes Kosh to realize that the very man who has hired him was responsible, many years earlier when Kosh was a child, for sacking Kosh's hometown and having his parents tortured and executed in the town square, forcing Kosh to watch the whole thing and then leaving him alive. But Gaar Suppoon had not recognized Kosh Kurp when he hired him; in fact, when Kosh angrily tells him "I was there," Gaar at first thinks that Kosh must have been one of his own soldiers! Long story short, Kosh kills Gaar in revenge and takes over his criminal empire, much to the delight of Jabba, who had always hated Gaar and who had known the whole story when he set the plan in motion.
In Legacy when Jariah Syn runs into the Jedi who killed his father he says he doesn't remember him at first. But when Syn describes the incident in some detail he does remember, and tells his side of the story. It turns out that his father was a pirate and was terrorizing a mining camp when the Jedi fought and killed him.
In Super Street Fighter, Juri calls out M. Bison for killing her parents and invoking this right before killing him. Sure enough, it was a Tuesday.Unfortunately for her, it's not actually Bison she's killing.
In one issue, Chromedome is using a Mental Fusion to interrogate the infamous war criminal Overlord. During the questioning, Chromedome brings up a traumatic incident when he was younger where Overlord gruesomely injured him at his workplace and kidnapped his mentor. Overlord doesn't really remember the event and couldn't care less anyways, as he's got bigger things on his mind. However after Chromedome accidentally lets a bit of important information slip, Overlord is motivated to think about it and manages to remember their encounter. This is a very bad thing, as it allows Overlord to flip control of the fusion to himself...
When Fortress Maximus gives Prowl a kicking, Prowl mentions that he's hacked off so many people that he's having trouble keeping track of them all, but whatever he did, he's sure it was for the greater good. What Prowl did in this instance was leaving Garrus-9 to the Decepticons, and Fortress Maximus to Overlord's hands, only sending in the Wreckers after three years to recover sensitive files, rather than rescue anyone.
The Transformers: Optimus Prime: Several hundred years ago, the forces of Onyx Prime killed the Torchbearers Praesidia Magna and Fastbreak, part of the events that shaped Pyra Magna's life and her dislike of Primes. When she finally gets a chance to confront him about this fact, Onyx who's actually Shockwave in disguise just shrugs them off as "two more nameless sacrifices".
Used rather darkly in Transmetropolitan when Spider, the Anti-Hero protagonist, is revealed to have left one of his previous assistants before he left the City in a bit of a fix by being grossly negligent or uncaring (or, considering it is Spider, both) — a seedy bar was using mood alteration devices to create illegal orgies and filmed their customers. Spider went undercover to reveal it, but only cared to protect himself, neither protecting nor warning said assistant. The results went about as well as expected for her and she's carried a grudge ever since. Spider doesn't recall her name when prompted about the event and doesn't seem to care.
Mister Rictus has hints of this in Wanted. At one point his mooks murder a boy's parents in front of him, and he orders them to leave the boy alive; his explicit hope is that the boy will swear himself to vengeance, and "give me someone interesting to fight in my old age." It's implied he does this sort of thing a lot.
Disney Ducks Comic Universe: It happens in "The Money Champ" (1959), Flintheart Glomgold's second appearance. In the beginning of the story, Flintheart suddenly appears in Duckburg and challenges Scrooge to a rematch. He had apparently spend the previous three years planning his revenge. Scrooge had never thought about his rival since their previous meeting, and he had several other adventures since their previous conflict. He both fails to recognize his opponent when initially challenged, and he has trouble recalling Flintheart's name.
Mickey Mouse Comic Universe: Played for a revenge plot in a modern Mickey Mouse story-arc from Italy. A businesswoman wants revenge from Mickey for rejecting her seduction attempts when they were teenagers, and for only having eyes for their classmate Minnie. Mickey does not remember her at all, has no interest in her still evident unrequited love, and basically tells that she should have moved on with her life instead of seeking revenge.
