Memory-Wiping Crew

When something dramatically outside of normality happens, and the Muggles are able to see past the Masquerade, a team (or at the least, a special go-to guy) is often dispatched to erase and/or alter the memories of any witnesses to cover up the abnormality of their mundane lives and keep the existence of the weird stuff a secret (often by using some sort of Laser-Guided Amnesia).

Note: This is not about the amnesia, or about what causes it. It's about WHO causes it. (No, not that WHO, either. Or is it...)

Compare The Men in Black, Cleanup Crew.

Anime

 * Darker than Black: Gemini of The Meteor features a faction of the military that serves as this for people whom get into contact with the super-powered Contractors. Witnesses that prove too difficult to catch are simply killed.

Film
"Rick Dicker: "We have to pay to keep the company quiet, pay damages, erase memories...""
 * Men in Black is probably the best example. Individual MIB teams had the neuralizer, which could wipe memories for a set amount of time and leave them in a hypnotic state so that new memories could be implanted. While they could often do the jobs themselves, and indeed it was part of their function, for larger memory fixing they could call in special task forces that would come out, neuralize large numbers of people, plant evidence, etc.
 * In Men in Black II they even use a gigantic neuralizer hidden in the Statue of Liberty, capable of wiping the memories of all New York City.
 * In The Incredibles, the government had a team like that, that would come in and wipe memories and implant new ones when an undercover Super would screw up and use his powers in the open.


 * Though it's also possible that they just paid any involved persons to never speak of anything related to this again.
 * Lacuna Inc, from Eternal Sunshine of the Spotless Mind are a non-MIB version, removing memories of bad relationships. They would even set up in the client's home so they would wake up without any idea that something had happened.
 * The Adjustment Bureau

Literature

 * The Temporal Corps of Simon Hawkes' Time Wars do this to any locals who get involved with them, though they made an exception for Jules Verne. Not wanting to interfere with the mysterious processes of creativity and stop him writing the books he was supposed to, he kept his memories of time travellers and submarines and such.
 * In the Harry Potter stories, if a wizard lost control and accidentally used his powers (or some other event that would endanger the safety of the wizarding world), the Ministry of Magic would dispatch a special group called Obliviators to see to it that people's memories of the event were altered.
 * Additionally, the charm used for such actions can also be used to wipe out people's entire memory, according to Chamber of Secrets.
 * In the Artemis Fowl series, the fairies can wipe the memories of any humans who learn about them, as they do to Artemis and his friends at the end of the third book (they all get better). There are even two different techniques they use. One is a block wipe, which just takes out a huge chunk of memory, but the longer the interval of time taken out, the greater chance there is for permanent mental damage. The other is a fine-tuned wipe which removes specific events, people, etc., but takes a lot longer than a block wipe.
 * In Red Handed, the Alien Investigation and Removal agency does this to recruits who don't make the cut.
 * In Memento Nora by Angie Smibert, there is a memory wiping company to erase memories of the frequent terrorist attacks. The book revolves around the main characters trying to remember those memories.

Live Action TV

 * Occasionally on Star Trek: The Next Generation when the crew would accidentally expose themselves (so to speak) to races that weren't ready for interstellar communication, the doctors would somehow do a little surgery to make those memories go away - basically an Alien Abduction. Dr. Pulaski was more prone to doing it than Dr. Crusher.
 * The Cleaners in Charmed. In order to keep magic a secret from humanity they remove the memories of anyone who sees a supernatural event.
 * UFO. The SHADO organization captures people who see real UFOs and has its medical department use a drug to erase their recent memories, thus preventing the public from learning about UFO attacks.
 * The Troop has a little alien whose song causes short-term memory loss so they can cover breaches of The Masquerade. However, ordinary ear plugs can protect one from the effect.
 * In Heroes, The Haitian is this.
 * One episode of The Night Stalker had Kolchak narrating the events into a tape recorder, because the government had done this to him, and it hadn't quite taken, or rather not all at once. His memory of the incident was fading rapidly, and he had to make the recording while he still remembered most of the details.
 * The Memory Police in Ultraman Nexus, who erased the memories of people who saw the Space Beast and Ultraman Nexus.

Tabletop Games

 * Hunter: The Vigil: As Task Force VALKYRIE are effectively The Men in Black, there's a good number of members dedicating to dosing witnesses of supernatural events with "Munin Serum," a chemical cocktail that clouds memories.
 * A typically dark example from Warhammer 40000. Since admitting the existence of an elite army of demon hunters would be admitting that there are such things as demons, the Imperium treats the Grey Knights as a state secret enforced by specially-trained psykers. Other space marines who fight alongside them go through a lengthy memory-scrubbing afterwards, while Imperial Guardsmen who distinguish themselves are subjected to a hasty process that is both painful and often fatal. Everyone else is just executed.

Video Games

 * In Sam and Max season 2, Agent Superball will emphatically deny time travel, even though the machine is parked right in the room. Any continued discussion of it will provoke him to employ his hypnotic, memory wiping powers. This is used for a puzzle later.
 * In the first "Knights of the Old Republic", the Player Character's memory is wiped out before the start of the game and replaced with another.

Web Comics

 * Early in The Kingfisher, Helen is used by Vitus as a one-woman Memory-Wiping Crew, giving Marc Laser-Guided Amnesia.

Web Original

 * The SCP Foundation: "Class A Amnesiac administered to all survivors."

Western Animation

 * Professor X often plays this role in early versions of the X-Men such as X-Men: Evolution, wiping memories when The Masquerade has been irrevocably blown. During an episode of Evolution where the Brotherhood show off their powers in the middle of a school football game, he dangerously overexerts his powers by modifying the memory of every spectator. Naturally, the one person whose mind he doesn't completely wipe is Principal Kelly...
 * Played with in The Movie of Phineas and Ferb.