Death Amnesia

"McCoy: You really have gone where no man's gone before. Can't you tell me what it felt like?

Spock: It would be impossible to discuss the subject without a common frame of reference.

McCoy: You're joking!

Spock: A joke... is a story with a humorous climax.

McCoy: You mean I have to die to discuss your insights on death?"

- Star Trek IV: The Voyage Home

Any case where a character who comes Back From the Dead remembers nothing about the afterlife. Usually done to preserve ambiguity about what the universe's afterlife is actually like, but sometimes we actually see the character in the afterlife before they come back with no memory of it. Fridge Brilliance dictates that this makes sense. Even if the soul exists, there's no reason for memory brain cells to record anything if the Ghost in the Machine is elsewhere while experiencing things; it would be less explainable if they did remember. In some cases, it turns out they don't remember because there was nothing there, or there wasn't one at all.

Compare Ghost Amnesia. Contrast Ghost Memory.

Comics

 * When Eric comes back in The Crow, he remembers very little of his former life except for Shelly, the names and faces of the people who murdered the two of them and an insatiable drive for revenge. The movie version wasn't able to portray this aspect of the story as well because Brandon Lee's accidental death occurred before some of the expository scenes were to be filmed.
 * Green Arrow's return to life in the Quiver arc was marked not only by him not remembering his death, but he also didn't remember several years of life before his death.

Film

 * Played with in Star Trek IV: The Voyage Home, as seen above. Spock seems willing to explain what it was like to die and be resurrected to Dr. McCoy, it's just that he can't. Apparently only two people who have died can discuss being dead. He's also unwilling to make metaphors that aren't precise.
 * In Dragon Ball Evolution, Master Roshi says after being resurrected by Shen Long that he was "in a wonderful place that he doesn't remember." He then proceeds to describe what happened there, in detail. This is the least of the movie's problems.
 * In the Casper feature film, Casper is asked what it was like to die. He answers "like being born... only backwards". Gee, that's helpful.

Literature

 * In Warbreaker by Brandon Sanderson, people who die a particularly heroic death are sometimes sent back to the living with a purpose. Only, they don't remember the afterlife, they don't remember the purpose, and for an extra twist they don't remember their previous life or death either.

Live-Action TV

 * Supernatural: Variation - Dean wakes up from a coma with no memory of his Near-Death Clairvoyance sequence. Playing the trope straight, Sam remembers nothing about the afterlife when Dean brings him Back From the Dead, and Dean remembers nothing after he's yanked out of Hell by Castiel. But it's also indicated that he has brief flashes of memory to what hell was like.
 * In that universe it's made clear that Hell exists, but it seems as though most people who die either stick around as ghosts for a while or "pass on" to some unspecified other afterlife. Maybe the only people who end up in Hell are the ones who made a Deal with the Devil.
 * Later revealed that Dean remembered every moment of it and had been faking the amnesia, so a subversion.
 * Its insinuated that he only remembers because Castiel pulled him out; demons apparently add Death Amnesia as part of the resurrection deal.
 * Torchwood has most of those brought back by the resurrection glove unable to remember anything, especially since they are panicking and only have 20 more seconds to live. In the end, it turns out from the one character that can remember it that there is no afterlife except for total darkness and ominous footprints, and that's why the others couldn't remember it.
 * This is later knocked into question when Owen is rendered into an undead state, and suggests that maybe mankind isn't meant to remember what comes after life.
 * Pushing Daisies: The last thing anyone resurrected by Ned remembers is the way they died.
 * The Sopranos: Tony's coma dream flows steadily out of his memory, with the exception of the beckoning light.
 * Darla, from Angel, claims to remember nothing between her death as a vampire and resurrection as a human, even though various hells clearly exist within the series, most likely because she lacks a soul. Her later ghostly appearance to Connor may suggest some more hopeful alternative, however.
 * John Locke from Lost claims to remember nothing after his death. Subverted by the fact that it's not really him.
 * Played perfectly straight by Lexx, which doesn't hold back from showing what its afterlife is like.
 * Happens to Daniel Jackson when he comes Back From the Dead - he can't remember what it's like to be ascended. Initially he can't remember details of his life before ascension either, but gets those back.
 * This is explicitly because the other Ascended wiped his memory, though: everyone else who gets bumped back to mortal gets to keep all their handy-dandy Infinite Cosmic Knowledge.
 * Until it overloads their puny human brain, of course.
 * In Star Trek: The Next Generation, when the Klingon mythological hero Kahless returns, Worf asks him about the afterlife, and Kahless claims he is unable to remember, since he is a traveller between worlds and is only able to retain knowledge of the world he currently inhabits. It turns out that he's actually a clone.
 * On Star Trek: Voyager, Neelix once had an existential crisis over this. His people hold that there exists a wonderful afterlife where he would be reunited with his family... but the fact that he remembers nothing after dying temporarily leads him to question his faith and reason for existence.

Mythology and Folklore

 * In Classical Greek Mythology, the dead were made to drink from the River of Lethe, which caused forgetfulness, before they could be reincarnated, making this Older Than Feudalism.
 * In Celtic Mythology, the dead can't speak, so they can't reveal anything about the afterlife. Truth in Television!
 * In Chinese Mythology, souls reincarnate, but before they enter their next body they have to drink some kind of tea (served by a fugly old woman) that makes them forget their previous life. This memory/memories can be recovered through aid from some powerful beings (or by Enlightening yourself), as happened in Journey to the West.

Tabletop Games

 * Characters in Dungeons and Dragons generally don't remember the afterlife after being raised from the dead, which is generally blamed on the "trauma of the experience". In most settings, it's possible to visit the places where dead souls go, but they generally remember even less about their lives than the undead.
 * The Planescape setting and various other materials like Planar Handbook or Manual of the Planes add a pseudo-science explanation for the above: when you die your soul passes through the Astral and leaves a "memory core" behind. When you're called back, your soul passes back through the astral and grabs its core again, which overwrites any memories formed in the afterlife. Once in a while, though, you might grab the wrong set of memories...
 * In Kult, this is explicitly caused by the machination of the Demiurge to make sure humans can't reach their true potential in the cycle of reincarnation. Once every other while though, some souls escape the mechanism, and thus an Enfante Terrible who remember the horrors of The City That Is Everywhere is born.

Video Games

 * In a Runescape quest, a cave goblin is killed and later revived with her memories of death missing. Whether her memory of it was erased or there is not an afterlife to remember is commented on but not explained. Of course, none of this cosmological ambiguity applies to player characters, who are immediately restored to life by the gods after payment in the form of wrist slaps.
 * Plus the fact that there are ghosts crawling all over Runescape and you occasionally help them pass on, destroys the ambiguity. Not that Zanik had seen any of them by that point.

Webcomics

 * Subverted in The Adventures of Dr. McNinja. This is supposed to happen, but Ben Franklin came back from the dead once before he remembers it the second time. But the part of the afterlife he got to (purgatory) isn't interesting enough to bother remembering anyway, and most people there don't even realize they're dead unless it's explained to them.
 * In Red vs. Blue Church promises Sarge that he won't suffer this... if he gives Church 5 bucks.
 * Order of the Stick probably adheres to this trope, viz. Roy's father having died six times and not done anything about his afterlife accommodations, but that may have as much to do with his own character than anything else.
 * Now that Roy has been properly resurrected, it's been confirmed that it's indeed this trope. All Roy apparently remembers of Celestia is a happy, wonderful blur. However, he has perfect recollection of his time spent as a ghost on the mortal planes, as well as his time on the cloud (the Celestial "waiting room"), and later mentions his mom, who he only met in Celestia.
 * Its Walky: Tony remembers no afterlife after being resurrected 2 years after his death, but an aftelife is shown towards the end of the series.
 * Whenever Oasis comes Back From the Dead in Sluggy Freelance, her memory is always fuzzy concerning the exact moment of her death and anything that happened between then and her resurrection. Though at one point she freaks both herself and her killer out by remembering something that happened while she was a corpse lying on the floor.

Web Original

 * Strongly averted in The Spoony Experiment when Spoony and his clone were talking about what the Original Spoony went through after his death. He said that it's "all pantheistic or some shit", where you become part of the earth, the trees, and all things living. It was kind of "gay" to him. The living Spoony replies, "YES! I'm not going to hell for jerking off!"

Well, now Kirk gets the joke. Am I right? *Gets killed by Trekkies*