Amnesia Episode

I forget how to describe Amnesia Episode here. Where am I?

Amnesia is in a unique position to provide drama for any sort of serial. It's scary to think that one's memories could suddenly be taken away, it can be used to take someone out of the action for a while, or it can be Played for Laughs, in which case, it will play off of Mistaken Identity. This is when an entire episode or story arc's plot revolves around a character getting amnesia.

Note that this trope only applies to works with an episodic nature, like a TV show or a comic book, wherein it is the plot for a single installment, and allows a familiar character to be Not Himself for a while, for humorous or dramatic purposes. Use of amnesia as part of the plot of a movie is usually not this trope, as it relies on the dissonance between the character and his amnesiac self for at least part of its effect.

Generally goes hand in hand with Amnesiac Dissonance, Easy Amnesia, Trauma-Induced Amnesia and sometimes Identity Amnesia (and many examples on those pages apply here as well). Not to be confused with Aesop Amnesia. Of course, the character may only be Faking Amnesia, too. If he's not, there is the risk of Amnesia Danger.

Super-Trope to Criminal Amnesiac (and many of its examples apply here, too).

Examples of Amnesia Episode include:

Anime and Manga

In the Excel Saga manga Excel gets amnesia and winds up living with Umi Rengaya and her family, including Professor Shiouji, who works for Kabapu, sort-of-arch-enemy of Excel's boss Il Palazzo. All the while, Excel is replaced by a fake Excel so neither Elgala nor Hyatt realize she's gone. In the anime, as well, during its one totally serious episode, Excel forgets who she is after getting shot by Il Palazzo, and winds up being saved by the Municipal Defense Force.
- Hyatt gets amnesia in the manga too, and ends up getting engaged to her neighbor Watanabe. Until Il Palazzo restores Hyatt's memories and she leaves with him.

Comic Books

In one Disney Big Bad Wolf comic, the wolf has a nasty fall when chasing the Three Little Pigs, gets Easy Amnesia, and Practical Pig convinces him he is a pig and got hurt when chased by a wolf. Cue Zeke Wolf becoming horribly scared of his own son...

Film

In The Muppets Take Manhattan, right after Kermit finds out that the production is a go, he gets hit by a car, and he loses his memory. He regains it as a result of Miss Piggy throwing him against a wall. Unlike most instances of film amnesia, this counts as the movie is one in a series, and Kermit is a well-known and familiar character.

Live-Action TV

Gilligan's Island actually had two of these, one with the Skipper and the other with Mary Ann, who thinks she's Ginger. When the Professor tries to snap her out of it with hypnosis, Gilligan ends up thinking he's Mary Ann. Obviously Played for Laughs.
It's Garry Shandling's Show: Nancy gets amnesia (Garry, of course, lampshades it: "Our first amnesia episode!") but gets her memory back using the flashback booth.
Good Eats: In the seventh season episode "Ill Gotten Grains", Alton Brown gets Easy Amnesia, but is still a brilliant cook. He's rescued by Francis Andersen (his "biggest fan" and a dangerously obsessed pastiche of Stephen King's Misery), who tells him his name is "Abe," and...

Francis: ...you're here to create wonderful wheat recipes for my store.
Alton: I am?
Francis: Yes, and...and you live here with me.

There was an episode of Monk where Monk gets bonked on the head, and a woman unscrupulously convinces him that he's her husband. This doesn't stop Monk from attempting to solve the mystery of the week, although it causes his OCD to become significantly less serious.
In an episode of MacGyver, the Villain of the Week takes advantage of MacGyver's amnesia to convince him that Peter Thornton is actually a terrorist to be apprehended, and even supplies him with a gun to do the job. Since Mac's memory has started to come back, though, and since he and Pete are such good friends, it doesn't take long for Pete to talk him out of it.
- In another Mac-Gets-Amnesia episode, the writers play around a bit. Since all the flashes of memory (played by clips from other episodes) he gets are of explosions or other violent acts with him in the middle, Mac almost convinces himself that's he's really a Criminal Amnesiac.
On Miami Vice, Crockett got amnesia while working undercover and began behaving as his cover identity would.
On The Dukes of Hazzard, Bo Duke got amnesia and Boss Hogg convinced Bo that he was Hogg's son.
In the episode "Tabula Rasa" of Buffy the Vampire Slayer, thanks to an overdone memory spell, everyone gets amnesia and has to try to work out their relationships to each other from what little clues they can find on themselves.
NCIS has an episode where Gibbs gets amnesia, thinks he is still a Marine, and gives himself the appropriate crew cut.

Western Animation

One episode of Batman: The Brave And The Bold has Batman getting amnesia while in his "Matches Malone" gangster persona and believing he is an actual crime boss.
One of the Captain Caveman and Son shorts on The Flintstone Kids had Captain Caveman get amnesia and assume that he was a villain because he was dressed as one (A domino mask). Interestingly, the entire criminal element of the city helps his son get him back to normal - Captain Caveman is such an effective thief that the city soon runs out of places that the other criminals can rob.
An episode of Aladdin had Princess Jasmine getting amnesia, and Harmless Villain Abis Mal convinces her that she's in fact his evil daughter, a desert bandit. She upgrades to a eyebrow-raising black costume (complete with whip) and helps Abis take over the country, but then betrays him and decides to promote herself to main villain after realizing he's an imbecile.
The Danger Mouse episode "Public Enemy Number One" had Baron Greenback convince an amnesiac Danger Mouse he was really a super-thief known as "The White Shadow".
Word Girl: The episode "Two-Brains Forgets".