Ret-Gone/Comic Books

Examples of in  include:

DC Comics Universe

 * Towards the end of Crisis on Infinite Earths, several universes have been subjected to this. Survivors find that in the new universe, nobody remembers that they ever existed. Those characters
 * There was a truly heartbreaking Christmas special a couple years after the Crisis where the ghostly superhero Deadman is wondering why he bothers going on when a young woman, who can see him, tells him: "We don't do it for the glory. We don't do it for the recognition... We do it because it needs to be done. Because if we don't, no one else will. And we do it even if no one knows what we've done. Even if no one knows we exist. Even if no one remembers we ever existed." Then she disappears into the night, but not before Deadman asks her name.
 * Animal Man:
 * The immortal Hamed Ali was literally erased from existence. His lines became sketchier, he lost his color, he became nothing more than rough pencil lines and design notes, and disappeared into nothing at all.
 * Animal Man gave us Comic Book Limbo - a space where all forgotten comics characters goes. As long as they are there, no one will remember them, and everybody will regain their memories about them when writers drag them from this terrible place and put in their stories.
 * This was the origin of Waverider. In a dark future ruled by a tyrant named Monarch, scientist Matthew Ryder time-traveled to the past to defeat him, suffering an accident that turned him into the time-travelling superhero. Waverider ultimately prevented Monarch from conquering the world, but in doing so history was altered, so that Matt Ryder never went to the past and never became Waverider. However Waverider still existed, and eventually joined forces with the Matt Ryder of the new timeline to form the Linear Men.
 * Linda Park, the wife of the third Flash, was Ret-Goned by a supervillain at her wedding, just before vows were exchanged. The groom found himself at home, confused and vaguely aware that something was missing, but unable to figure out what it was. Eventually (a year and a half later) she was restored to her proper place and the ceremony resumed.
 * Although Bart Allen (Impulse) could still see and remember her. Of course, his grasp on reality is a little off.
 * Donna Troy's (again) Retcon-ed origin involved her being cursed by a character called the Dark Angel to live a life full of pain and suffering, with her life being restarted and erased from the world's memory—again—when Donna was at her lowest. (In the most recent case, the death of her ex-husband and son, coupled with the loss of her powers). Hippolyta (the Wonder Woman at the time) & her Teen Titans teammate Wally West (The Flash) remembered her due to being outside the timestream when it was rewritten, and Donna was restored to her previous form, complete with powers (because they used Wally's memories to restore her, and he remembered her best with her Wonder Girl powers).
 * The tragic part turned out to be that Wally didn't have much memory or knowledge of the (well-written and positive for both of them)relationship she had had with Green Lantern Kyle Rayner before her latest Ret-Gone - and so of course she came back with only the vaguest memories of her time with him. Then again, that could just be the writers playing with the readers, like the Magnificent/not-so-Magnificent Bastards they tend to be...
 * A later version of The Dark Angel tried to do this to Post-Crisis Supergirl by trapping her in a horrifying illusion without her knowledge. If Supergirl had mentally, physically, or spiritually broken, Dark Angel would have had the authority to erase her. Supergirl survived the test, but Dark Angel decided to erase her anyway, only to be stopped by her boss, The Monitor.
 * In Legion of Super-Heroes, the need to get Mon-El out—because he was written out of Superman's existence—resulted in a confrontation between the Time Trapper and Mon-El. The Time Trapper explained he was behind Mon-El's origin and Mon-El would retroactively cease to exist if he killed him. Mon-El declares that other heroes will arise in his place, and kills him. Fade to white.
 * DC's second Chronos removed himself from history, since this was the only way to prevent his adoptive mother being killed in a car crash. Due to the nature of his powers, he continues to exist, but no one remembers him
 * This is one of the higher-end abilities of Darkseid's Omega Beams in New Gods.
 * In the final issues of Shade the Changing Man, Shade (and Milligan) attempted to invert this, and remove Kathy's tragic backstory . It made for an anticlimactic ending, as Shade's personality had come full circle to the socially awkward idealist he was at the beginning, the final page left hanging on his clumsy attempts to reconcile with a woman who no longer had a history with him.
 * As revealed in Justice League Dark, it didn't work. Shade's creation isn't really Kathy, and Shade has gotten so screwed-up as a result, he's no longer sure if there was ever a real Kathy.
 * Pre-Crisis, Supergirl fought a villain named Black Flame whose plan to defeat her was to trick the heroine into attempting this. Claiming to be a descendant of Supergirl from the future, Black Flame committed a few random acts of vandalism, and then "generously" let her "ancestor" see archived recordings of the future, where she ruled as a cruel and murderous tyrant. In truth, the archives were fake, and Black Flame was a citizen of the shrunken city of Kandor; she had hoped that Supergirl would expose herself to gold kryptonite to erase her powers to prevent any descendants from having them - which, of course, would render her helpless while not getting rid of Black Flame at all. There was one flaw in the villain's plan -

Marvel Comics Universe

 * In the She Hulk story "Time of Her Life", the Time Variance Authority's method of execution is the Retroactive Cannon, AKA the RetCan, which does this to anyone shot with it. Including, in that very story, Knight Man and Dr. Rocket. Who, you ask? Well, isn't that the point... Oddly, this method has a safety catch applied in order to prevent most temporal paradox scenarios, as it alters history to replace the victim with someone else -- if it can. The testimony at Jenn's trial was not to argue that the sentence was unwarranted or undeserved, but to prove that her role in history was irreplaceable.
 * In a X-Men storyline, the New Mutants (a group of teenage mutants being trained as the next generation of X-Men) were RetGoned by a Sufficiently Advanced Alien called the Beyonder. The only one to remember their existence was Kitty Pryde, who had a magical connection to one of the New Mutants that even the Beyonder's godlike powers couldn't erase.
 * X-Men: Legacy introduced a character named "Forget-Me-Not", a member of the X-Men whose mutant power made everyone forget he existed the second he moved out of their vision. That's right, this guy is a member of the core team of mainstream Marvel, and has been so since M-Day at least; his heroic actions include fighting the Brood, acting as a soldier during the Age of X, and saving the other members from death, enslavement, and many other horrid fates dozens of times, but due to his powers, nobody ever remembers him, and his contributions remain uncredited and ignored. To be frank, he was used tongue-in-cheek to explain why certain bad guys tend to have something happen to their super awesome weapons at the last moment and things like that. (Why did the team luck out and escape that death trap that seemed flawless? Forget-Me-Not sabotaged it. How could they have survived those rigged explosions that were strong enough to vaporize the island? Forget-Me-Not disarmed it. He seems to be the catch-all way to describe any confusing Deus Ex Machina in the Mutant Books.) The only one who remembered him was Xavier, who put in an "alarm clock" telepathically to remind him of his existence and the guy took it hard when Xavier died during Avengers vs. X-Men
 * The situation with Spider-Man's children, if any, was always pretty vaguely defined and caught up in Continuity Snarl. All of them are eliminated wholesale as a result of the One More Day storyline; his now-impossible future daughter even (somehow) shows up to chew him out for being an idiot and taking a Deal with the Devil just before he goes through with it. Fortunately, she's still alive and starring in her own comic in an Alternate Continuity.
 * Another Spider-Man example: "retcon bombs" are the preferred weapon of Hobgoblin 2211, the daughter of that era's Spider-Man. Their first victim is her boyfriend, who helped her escape from her VR prison in the first place.
 * A one-shot 1970s Spidey enemy was Drom the Backwards Man, who was continually growing younger. When Drom gets killed, Spidey realizes that by the nature of Drom's affliction, all memory that he ever existed will probably vanish as well. So Peter narrates a record of the incident on a tape recorder for himself. Just as he finishes the recording, he forgets what he had been talking about.
 * In the Marvel Universe this is the stated purpose of the Ultimate Nullifier - a piece of KirbyTech which will erase the chosen target from history, completely. With the unfortunate side-effect that if the target is imperfectly visualized in the user's mind, the user is the one who's erased. Of course how you can determine if a firing succeeded or failed...
 * Marvel Adventures changes the effect of the weapon completely: it only nullifies differences in power, so that anyone can beat anyone, which is why it can be used to defeat Galactus.
 * In Marvel Comics, the Sentry's entire backstory is that he got Ret-Gone'd, which is why nobody remembers the character from Silver Age comics, even though he was active and present then.
 * Speaking of Marvel, Stryfe is forced to keep Cyclops and Jean alive so that he can be born.
 * This would have happened to Chase in Runaways had he sacrificed himself to the Gibborim to save Gertrude. There would be no trace or memory that he ever existed.
 * In the conclusion of the original Spider-Woman comic series, this was supposed to happen to Spider Woman. After being unable to return her soul to her body, she requested that her friend Magnus casts a spell that makes everyone forget that she ever existed. In the end... the spell was faulty, and she's Back from the Dead.
 * In a Marvel What If issue, a hero team calling themselves the Avengers formed in the 50s, rather than the 60s as is canon in the main Marvel Universe. In Avengers Forever, Wasp and Captain Marvel (from the present and future Avengers teams, respectively) meet these Avengers, much to their confusion, as they know damn well the team never existed in their timeline, and this is supposed to still be their timeline. The discrepancy is explained by the arrival of Immortus, who wipes out the standing section of time (nearly taking Marvel and Wasp with it) in order to prevent a confrontation between Earth and the Skrull Empire, who had one of its agents impersonating Not-Yet-President Nixon. The now nonexistent Avengers team was later resurrected and reinstated in their place in the 50s as a different team, known as the G-Men, who later became the Agents of Atlas. Phew.
 * Invoked once by Doctor Strange—to clear his schedule so that he could chase down and defeat a mystical enemy, he cast a spell which made the entire world believe that he had died years ago, and that the physical man they saw was a harmless occult expert named "Stephen Sanders."

Vertigo

 * Neil Gaiman seems to be a fan of this. In addition to Neverwhere, he also used this in the Sandman arc "World's End".
 * Implied in Fables. The Jack of Fables and Fables crossover even has the villain doing this to Little Black Sambo; after Revise had more or less done this to him by censoring his myth.

Other publishers
"Michael: Wait! Others? What -- Uh -- What do most people choose? Do they forget, or-- (For a moment, he thinks that he sees a twitch of a smile under that burlap hood.) Hanged Man: No one forgets. No one. Good night, Michael Tenicek. Sleep well."
 * The subject of "The Nearness of You," a bittersweet issue of Astro City in which a man keeps dreaming of a woman he's never met and all her intimate details. It turns out that she was his wife and they were deeply in love, but a supervillain has just made an attempt to control all reality. He was thwarted (it's strongly implied that a Crisis Crossover took place while nobody was watching), but the heroes couldn't restore time exactly how it was before. Her grandparents never met in this new history, and so the man's wife never existed. The man has Ripple-Effect-Proof Memory thanks to their strong love. The Hanged Man (a very powerful Astro City hero) appears to the man, explains the situation, and then gives him a choice: he can either have all his memories of her erased so that he'll no longer be haunted, or he can continue to remember the perfect, pure love of his life—knowing full well that he'll never get to experience it. The man chooses to remember. When the Hanged Man excuses himself and says that he has others to visit, the man asks:


 * Also in Astro City, one of Samaritan's powers (as well as his nemesis Infidel) is immunity to becoming Ret-Gone. Samaritan has already averted the grim future from which he came, and as a result he was never born (an automated taco stand was built where his house was supposed to be.) Once, Infidel accidentally wrote everything out of continuity except for him and Samaritan, at which point they realized that it was pointless for them to keep trying to kill each other.
 * In fact, two of the stories featuring Samaritan strongly hint that the reason why he's been obsessively doing good acts ever since the success of his first mission is to make up for deleting the loved ones of his original timeline. Talk about Survivor's Guilt!
 * Rayek in Elf Quest: Kings of the Broken Wheel wants to take the Palace forward in time and merge it with its former self before it went back in time. This, he claims, will erase the entire history of the elves, trolls and preservers, except for those who happen to be in the Palace when the paradox doesn't happen. Confused? In the event, he does take the Palace forward, leaving behind a whole bunch of elves and trolls who are afraid they'll suddenly cease to exist at some point.
 * One comic I don't remember the name of (appeared in the Swedish edition of The Phantom): a teenage time traveller is hiding in the present day, trying to avoid futuristic robots that want to kidnap him (because he knows of their existence). When the robots find out where (or rather, when) he is, they try to zap him into their time, but they keep getting the wrong kid... and every time, everyone forgets the victim's existence, as though they never existed. The only ones who remember is the time traveller, and the normal kid protagonist (due to some Phlebotinum).