Ophelia: You drank the venom but didn't die?
Mechtild: They found my corpse, threw me away, and declared the Devil vanquished. I had my remedy laid by and so, I lived.
When William Shakespeare put Juliet into a death-like state in Romeo and Juliet, he was probably using a trope that was already lying around. He may have grabbed it from an old Celtic precursor of Sleeping Beauty.
Anyway, this one has some years on it.
In this trope, people who are not dead appear to be dead and, like Human Popsicles, do not age. Because they look like that, all kinds of ugly stuff happens, either to them or to the ones they love, up to and including being kissed by princes. As to what causes this condition, there can be a range of causes including drinking potions, eating dodgy food, pricking your finger on sewing equipment, triggering some kind of curse and so forth.
When intentional, it's a kind of Faking the Dead or potentially Death Faked for You; the character may be trying to get out of a bad situation or protecting loved ones, so they deliberately invoke this to pretend to die more convincingly. Unfortunately, it may work a little too convincingly, which can lead to unpleasant situations such as being Buried Alive, getting autopsied/embalmed, or their loved ones freaking out from grief. If someone is merely sleeping the sleep of the dead, but life can be discerned, see Deep Sleep. Occasionally overlaps with Angst Coma.
Supertrope of King in the Mountain. Related to Disney Death, where the other characters/the audience is led to believe a character has died only for them to turn out to be alive after all, and they frequently overlap. It may lead to Reports of My Death Were Greatly Exaggerated.
Due to this trope often being used as a Plot Twist, beware of unmarked spoilers.
- Zabuza Momochi in Naruto. Also Faking the Dead, because Haku used this trope to protect Zabuza from Kakashi and his squad.
- Griffith of Berserk blackmails Foss, the leader of the conspiracy to kill him, into placing a drug that does this into his goblet instead of the poison the conspiracy intended to be placed as part of his masterful Batman Gambit that ultimately leads to the Queen and her nobles being locked inside a burning castle to die.
- After Wolfram's heart is stopped in Kyou Kara Maou!, his body is put in a nice little magical life-support box until his fiancé, Yuuri, can defeat the Big Bad and get him going again. It's kind of up to interpretation if he was actually at any point dead or not, but Yuuri certainly has a strong opinion that he wasn't.
- Played for laughs in an episode of Black Butler Grell, a Grim Reaper, took a nap in a field and woke up at the Undertaker's. Noting afterwards that she probably should remember to breathe next time.
- Snow White and the Seven Dwarfs: The evil queen tricks Snow White into eating an apple dipped in a "Sleeping Death" potion, that causes her to fall into such a deep sleep she'll appear dead, and the only cure is true love's kiss. The queen assumes that the dwarfs will bury Snow White alive due to believing her truly dead, but they instead craft her a glass coffin and keep vigil over her side, enabling the prince to revive her by kissing her.
- Happens to the male lead in Cirque du Freak: The Vampire's Assistant. After Darren takes a drug to make it look as if he's dead, Crepsley finishes the job by snapping the boy's neck and pushing him off a rooftop. Darren is buried, and Crepsley dugs up his grave. Now Darren can start his new life as a vampire.
- The Crime of Dr. Crespie: Doctor Andre Crespi hates Stephen Ross, who married his ex-sweetheart. Ross must undergo surgery and Crespi, sensing an opportunity, seizes it. Ross appears to die, but Crespi has given him a drug that induces a state of apparent death. Ross retains all of his senses and is buried alive. The other doctors become suspicious. They exhume the body and return to the hospital to prove he was poisoned. Ross awakens from the drug while on the autopsy table.
- The Illusionist: Sophie fakes her death as part to trick the police. After a drunken argument, the Prince "kills" Sophie, and after a search, police and Eisenheim find her body in the river. She used fake blood and a potion to appear dead.
- John Carter: When John is banished back to Earth, he takes puffer fish toxin that puts him into a death-like sleep to throw the Therns off his trail.
- Happens to poor Frodo in The Lord of the Rings: The Return of the King (or The Two Towers, if you go by the literature) when Shelob stings him. His death-like state is convincing enough for Sam, at least, until the point when the Orcs take Frodo and explain that he's still alive in Sam's earshot, at which point Sam decides to follow them to the orcs' barracks to get his Big Damn Hero on.
- While fleeing an angry mob come to burn her as a witch, Mechtild drank a potion containing snake venom that caused temporary paralysis and collapsed near the edge of the forest. She appeared dead to the mob, who dumped her 'corpse' in the woods, enabling Mechtild to drink the antidote once the effects began to wear off and go into hiding.
- Ophelia fakes her drowning death by ingesting the same potion, taken from Mechtild's hovel. She looks dead to everyone save Horatio, who had figured out the truth and digs up her coffin after the funeral as she instructed. In Ophelia's case, she took a little too much and needs Horatio to help her get to Mechtild in time to drink the antidote.
- The Premature Burial: Guy Garrell is consumed with the fear of being buried alive. His worst fears come true. He goes into a cataleptic state, and is declared dead. His family thinks he died of a heart attack. He's buried in the cemetery, but is miraculously dug up by grave robbers.
- As Holmes surmises at the end of Sherlock Holmes (2009), the villain, Lord Blackwood, was able to fake his seeming-execution by hanging by using a harness to survive. Blackwood was also able to fool Watson, the physician charged with checking his pulse and declaring him dead, thanks to a potent toxin taken from a Turkish plant that suppresses the pulse and induces the subject into a comatose state. He was then able to dramatically shatter his own grave and "rise from the dead" by having the slab pre-shattered and then glued back together with an adhesive made of egg and honey that can be washed away by the rain.
- In Superman Returns: Everyone laments Superman's apparent death. But when Lois and Jason go to see him, there a (very clear) faint heartbeat on the monitor. He hasn't even died! It's visible as Jason and Lois leave the Daily Planet that Perry White has two templates of the front page prepared ahead of time: one announcing Superman's death and the other announcing his recovery.
White: Always be prepared.
- Arthurian Legend: King Arthur is sleeping until his return — hence "The Once and Future King".
- In The Blue Mountains, any man who comes to the princess's castle and doesn't ask what is happening ends up like this.
- Any version of "Sleeping Beauty" (see here for a list of many) will feature some variation of this. In most versions, the princess pricks her finger on the spindle of spinning wheel and falls into a deep sleep, waking after a prince kisses her.
- This happens in just about any version of "Snow White" (see here). In most versions, she eats a poisoned apple given to her by her Wicked Stepmother that leaves her comatose. Everyone mistakenly thinks she's dead, though luckily they can't bear the thought of burying her and instead craft her a glass coffin to keep watch over her. Depending on which version you read, she wakes up either when the piece of apple is dislodged when the prince accidentally drops her coffin, or when the prince kisses her.
- Sun, Moon, and Talia is the story that influenced "Sleeping Beauty". In this version, the princess falls asleep after getting a splinter of flax in her finger. Then a king turns up. We'll warn you though, this version isn't nearly as romantic as the later adaptations; the king rapes the unconscious Talia, causing her to become pregnant and give birth to twins. One of the babies sucked upon her finger and managed to suck the splinter out, after which Talia is revived. "Sleeping Beauty" and its adaptations tend to remove that last part.
- The Count of Monte Cristo: the count gives Valentine a pill that makes her appear dead. She's buried in the family crypt. The count then carries her off to the island of Monte Cristo. For a month, Maximilian believes that Valentine is dead. Which causes Maximilian to long for death himself. Monte Cristo then reveals that Valentine is alive. The lovers are reunited.
- Sacred Hearts: Serafina fakes her death to escape the convent. She drinks a potion (given by a nun) to make her appear dead. Her coffin gets smuggled out and she reunites with her lover.
- The Glassblower of Murano: Corradino fakes his death to escape Venice's Council of Ten. He drinks a vial that makes him appear dead. He's buried in a sack, and manages to dig his way out.
- In Dragon Bones, there is a sleeping (not like Smaug, really the "doesn't age, doesn't wake up" kind of sleep) dragon under a hill near castle Hurog. Major Spoiler: It's Oreg. Okay, he's only quarter-dragon, but can shapeshift to dragon. Turns out, that's his real body. The one Ward killed was kind of just a copy.
- In Neil Gaiman's Snow, Glass, Apples, a Grimmified Perspective Flip where Snow White is a bloodthirsty vampire, the evil queen is a benevolent ruler who put Snow White into a deep sleep to protect the populace, and the prince who accidentally woke her is a necrophiliac.
- Happens to poor Frodo in The Lord of the Rings: The Two Towers (or Return of the King in the Jackson-films) when Shelob stings him. His death-like state is convincing enough for Sam, at least, until the point when the Orcs take Frodo and explain that he's still alive within Sam's earshot, at which point Sam decides to follow them to get his Big Damn Hero on.
- In Graham McNeill's Warhammer 40,000 Ultramarines novels, Roboute Guilliman is seen in his stasis tomb, and we are told of legends that he is healing from his wound and will arise again.
- A state that Granny Weatherwax enters in Discworld whenever she's Borrowing. It had caused her enough unnecessary embarrassments (being a very old woman who lives alone) that she now wears a small cardboard sign with the words "I Aten't Dead".
- Little, Big draws on the legends that German emperor Friedrich Barbarossa is asleep under a mountain by having him wake up.
- InThe Master Mind of Mars, Ras Thavas does this to preserve the bodies he swaps (or swaps parts of). When Valla Dia is in danger, Ulysses Paxton resorts to it as the only way to hide her safely.
- In the Disney movie John uses pufferfish tetrodotoxin to lure a Thern spy out of hiding so he can steal his medallion and use it to return to Mars.
- In Arthur Conan Doyle's The Poison Belt, people start dropping like flies as the Earth passes through the poison belt. Professor Challenger uses bottled oxygen to keep himself and the other protagonists conscious for a few hours so that they can observe the death of humanity before joining it in death; they're all very surprised to wake up and find that they're alive. And even more surprised to find, some twelve hours later, that everyone else wakes up too! (Well, except for the ones who'd been killed in the accidents and fires that occurred when everyone first passed out.)
- In Robert E. Howard's "The Devil in Iron" Conan the Barbarian finds a castle appearing where he knew there had been a ruin, and inside, a woman who has just woken up, thinking that historical events were just last night.
- In "Jewels Of Gwahlur", Yelaya.
- The immortals of The Madness Season have a technique that allows them to impersonate a walking corpse. The most skilled ones are able to temporarily stop their metabolic functions. The hero's father ultimately died when he went too far in his corpse transformation. Daetrin himself almost wound up doing the same.
- A number of characters in stories by Edgar Allan Poe were prone to catalepsy (see Real Life, below), such as Madeline in "The Fall of the House of Usher".
- In Ruth Frances Long's The Treachery of Beautiful Things, when the nix steals her soul, Jenny. The forest folk lay her out on a bier, like Sleeping Beauty.
- After the titular character of The Saga of Darren Shan was turned into a half-vampire Mr. Crepsley faked his death by carefully breaking his neck without severing his spinal cord and drugging him so that he seemed dead. Later digging him out of his grave.
- In Lawrence Block's The Canceled Czech Evan deliberately triggers Kotacek's catalepsy in the hope the Stern gang members who want to execute him for Nazi war crimes will believe he had a heart attack. While the ruse succeeds, the disappointed members decide to emulate the Bible by removing Kotacek's foreskin.
- Harry Potter and the Chamber of Secrets: When Mrs Norris the cat is found still and unresponsive, it's initially believed she's dead but the Hogwarts staff quickly deduce she's actually Petrified; she's still alive but unable to move or react (it's further indicated those who are Petrified are essentially unconscious too). Several students suffer the same fate and can't be cured until the school's mandrakes have matured enough to be made into a restorative potion. It's revealed a Basilisk is responsible; looking a Basilisk directly in the eye will kill a person or animal, but if someone looks only indirectly (such as via a reflection or through a camera) they just get Petrified instead.
- Night World: Those who are successfully turned into vampires appear physically dead for the final stage of the transformation, before they revive. James takes advantage of this when he turns Poppy; he makes it seem she died of the terminal pancreatic cancer she was recently diagnosed with so as to keep the Night World a secret while still saving her. Poppy even likens it to Juliet in her tomb; she herself is unconscious and dreaming in this state. James does have some obstacles to overcome; he has to mind control Poppy's parents and the funeral staff into not doing any autopsies or embalming, and ensuring they choose burial over cremation. He also has to sneak into the cemetery late at night to dig up Poppy's coffin with her brother's help.
- Starting with the novelization of The Death of Superman, this trope has been used to explain how Superman somehow survived his devastating battle against Doomsday while the rest of the world believed he had died. In the novel, it's explained that Superman had drained so much of his solar power reserves battling Doomsday that he went into something of a "power saver" mode that required just some time in the sun to fix. However, the humans all believed Superman had died-died and put him in a grave that could have made the death permanent had it not been for Project Cadmus.
- The Black List: In order to disappear from Reddington's watch, Liz has her ex-boyfriend (who is a doctor) use a certain drug to slow down her heart rate. The drug gave a very convincing illusion that Liz was dead after giving birth to her daughter. There was even a funeral. A few episodes later, Liz is revealed to be alive.
- Jane the Virgin: Rose, aka Sin Rostro, gives Janes husband (Michael) tetrodotoxin to slow his heart rate down making it seem like he died. She had her personal EMT drivers take him away and went on to blackmail the morgue pathologist to sign his death certificate. There's an emotional funeral. Four year later its revealed that Michael is alive. But he has amnesia from electroshock therapy.
- Prison Break: Michael is forced to work for Poseidon. He fakes his death to protect his family. We see his "corpse" in the season 5 premiere. When Lincoln digs up Michael's grave, his body is gone.
- Queen of the South: Teresa is shot to death. We see her body in the mortuary. But nothing is as it seems: she faked her own death to escape drug criminals.
- Days of Our Lives:
- Vivian used an herbal medicine to put Carly into a death-like state. It was so convincing that Carly was considered dead and buried. But then she woke up underground in a coffin equipped with lights, an air tank, and a two-way speaker system. Vivian eventually confessed to her nephew, Lawrence, and Carly was rescued just as she was running out of air.
- Will was strangled, but did not die. Dr Rolf found Will to be unconscious but breathing. He then injected Will with something that would make him appear to be dead. After Lucas and Sami had viewed Will in the morgue, Dr Rolf revived Will with his serum. Will's family unwittingly buried an empty coffin at his funeral. When Will is discovered to be alive, he's suffering from amnesia (a side effect from Dr Rolf's serum).
- Passions: Sheridan Crane's death was faked (to escape criminals who were pursuing her) and she was buried to continue the ruse. Unfortunately, plans to rescue her immediately were hindered when the criminals in question kidnapped her would-be saviors, leaving her in considerable peril (Sheridan's claustrophobia didn't help matters much). Although she was ultimately rescued at the end of the "day", the scenes played out for over a month.
- General Hospital: Jerry orchestrated the abduction and faked death of Robin Scorpio Drake. Patrick finds Robin in a tomb and kisses her. Robin wakes up and reveals she faked her death by taking a drug to slow her heartbeat.
- Lost: Paralyzed by spider bites into a death-like state, a couple are buried alive. They died rich, though, so it wasn't a complete downer.
- Jack Bauer in the season 4 finale of 24, when he found it necessary to fake his own death in order to prevent being Killed Off for Real. Coupled with his being clinically dead for several minutes during season 2, it inspired the Jack Bauer Fact "Jack Bauer died for his country and lived to tell about it. Twice."
- River and Simon do this in Firefly to get into a hospital. Later, Tracy uses it as a way to run away.
- Happens at least once to Sloane on Alias, which also featured many other examples of Faking the Dead.
- On one episode of The Master (a.k.a. MST3K stalwart Master Ninja), McNinja master McAllister (Lee Van Cleef) reveals that he can accomplish this by meditation; this turns out to be an example of Chekhov's Skill.
- There's a grand tradition of this in Xena: Warrior Princess, dating all the way back to Xena's "death" by poisoning towards the end of the first season. (Since the trope was still fresh at the time, the resulting mourning process among her friends is thoroughly affecting.)
- Tek Wars tried fooling an AI with the Human Popsicle trick, because it detected the Cryo virus to still be active. Said AI figured they were finally killed by the stronger-than-normal setting of the Cyro tube.
- It is rather unclear whether Babylon 5's Captain John J. Sheridan really died on Za'Ha'Dum or if Lorien kept him suspended in a state near death (between tick and tock). Lorien says "He was dying, he was dead" but he has a tendency to be vague. Zack Allen doesn't know anymore, and Michael Garibaldi is skeptical. In either case:
Drazi Ambassador: We thought you were dead.Captain Sheridan: I was. I'm better now.
- And later:
Captain Sheridan: Death! Been there. Done that.
- And later:
- Cameron gets one in the Stargate SG-1 episode "Babylon", in order to get out of a revenge duel to the death.
- Captain Kirk, from Star Trek: The Original Series, had a rather 'Romeo and Juliet'-esque faux death in "Amok Time", that was caused by the Doctor...of all people.
- On Heroes, Sylar tricks the Company's doctors into removing his restraints by stopping all of his vital signs.
- Inverted in legendary fashion in the Parrot Sketch.
- Fraser did this on Due South with an Inuit concoction that slowed his body down.
- Arthur did it on Merlin to lure his father into crying the tears of true remorse needed to break the troll magic spell. He did, however, require an antidote to stop the potion he took killing him for real.
- In Doctor Who, the Time Lords have the ability to temporarily suspend their life functions, making them appear to be dead. The Doctor does this on more than one occasion and Romana uses this trick to escape from the Daleks' slave mines in "Destiny of the Daleks".
- In the Miami Vice episode "Tale of the Goat," a voodoo chief uses tetrodotoxin to fake his death so he can be smuggled into Miami. Later, cultists inject Tubbs with the poison, almost killing him.
- Father Brown: Happens to Father Brown in "The Wrath of Baron Samedi" when he is drugged with a poison that lowers his heart rate to the point where he appears to be dead.
- Legacies: Dana is bitten by Arachne, a giant spider. Her body is found in the woods, seemingly dead. A few moments later, she gets up and leaves. Unfortunately, the poison liquified her from the inside. She literally pukes out her guts, vomiting herself to death (for real this time).
- Thriller: an aging millionaire survives being buried alive, but his devilish fiancée plans to take advantage of his next cataleptic seizure, by marrying him and then making sure he stays in his grave.
- Silent Witness: At the end of "Trust: Part 1", the forensic pathologists receive what appears to be a dead body of murder victim. However, he was actually just paralysed from pufferfish venom. In the next part, he wakes up and walks right out of the morgue, grabbing a scalpel in the process. It's just as well, because he was due to be autopsied next.
- The Irish folk song "Finnegan's Wake".
- Juliet, of course. Friar Laurence gives her a potion to make her look dead. She's buried in the Capulet tomb. She woke up to a dead husband. Ouch. There goes the honeymoon.
- Imogen: not feeling well, takes a potion given her by Pisanio, thinking it's a medicine. The potion puts her into a deathlike trance.
- Naked Snake in Metal Gear Solid 3: Snake Eater has a pill that can induce this state to fool enemies into believing him dead. If you let him go too far before using the revival pill, however, he really will die.
- King's Quest VI: Heir Today, Gone Tomorrow allows protagonist Alexander to fake his death with a potion that actually does kill him, but then wears off after a few minutes. The in-game purpose of this is to fool a spy into reporting to the Big Bad Vizier in order to lower the security at the castle you inevitably have to infiltrate, but the actual purpose (because the security is the same either way) is to trigger a cutscene in which you can see the genie's lamp, so that you can replace it with a fake one later on.
- Hitman: Blood Money. A special drug used originally in mission 3, to get a target out of a rehab clinic without actually killing him. The second time it is used is on 47 himself, courtesy of Diana. Admittedly, she does this to save his life.
- The Elder Scrolls IV: Oblivion features this as part of an Assassin's Guild quest - the player needs to cut the target with a poisoned dagger to fake his death in front of someone who is trying to kill him for real.
- Guybrush Threepwood pulls this off in The Curse of Monkey Island with a combination of alcohol and a homemade hangover cure. Twice. On the same people.
Griswold Goodsoup: Oh, dear. He's had a sudden and completely unexpected relapse of death!
- In Team Fortress 2, the Spy can pull this off regularly with the use of his Dead Ringer watch.
- A key piece of the mystery presented in Dark Tales: The Premature Burial (inspired by the Poe story of the same name) is the fact that Victorine had a medical condition that made her prone to this.
- Tessa of S.S.D.D. was once mistaken for dead after being shot with a tranquilizer-coated bullet due to her artificial heart not having a pulse.
- In Roomies Codrus tried to get his former superiors in the Fox Empire off his back by faking his death with a potion. Unfortunately, it temporarily turned him into a zombie when he revived early.
- In the final episode of Super Friends "The Death of Superman", Superman is irradiated with Kryptonite while Firestorm is briefly captured. When Firestorm frees himself and gets to Superman's side, he finds him and fears him dead, which the others feel as well. After his funeral, in which they send him into the sun, the team goes to the Fortress of Solitude and, while they're getting Superman's stuff in order, the Superman Robot there tells them of a trance that Superman can use to slow the radiation poisoning. They realize Superman is in that state when Firestorm realizes he found him like that and the heroes race to rescue Superman before he really does die and Darkseid and his minions invade Earth.
- Truth in Television:
- The right amount of pufferfish toxins can cause a person to appear to be dead to even doctors. There have been several cases where people have been declared dead and returned, especially in Jamaica, where this method factors heavily into local Zombie Lore.
- The toxin of an Australian blue-ringed octopus, which paralyzes the victim and stops their breathing (and sometimes causes temporary blindness and deafness as well) but doesn't kill immediately and does wear off eventually. If somebody has the sense to perform rescue breathing until the paramedics arrive with mechanical assistance, the victim can make a complete recovery. If not...
- Several types of snake venom can mimic brain death. Victims are comatose, develop areflexia, ophthalmoplegia and loss of brain stem reflexes.
- An overdose of drugs (Baclofen, Barbiturates, Bupropion etc.) can mimic brain death. They cause hypothermia, seizures, and profound coma. However, once the drug is eliminated from the body, consciousness returns with no lingering harmful effects.
- Catalepsy is a medical condition in which the sufferer will sometimes enter a rigor mortis-like state in which they appear to be dead. 
- Clinical Death means that the heart and circulatory system has stopped functioning. Up until the 20th Century, this was the official definition of death. Even today it usually means your ticket's been punched. But, thanks to modern resuscitation science, death can no longer be considered an absolute moment but rather a process that can be reversed even many hours after it has taken place. If medical interventions do not exist at any given time or place, then of course death cannot be reversed. 
- The Lazarus syndrome is defined as a delayed return of spontaneous circulation (ROSC) after CPR has ceased. In other words, patients who are clinically dead sometimes spontaneously return to life. Occurrences of the syndrome are extremely rare, and the causes are not well understood. A possible theory is the delayed action of drugs, due to build-up of pressure in the chest. 
- Hypothermia: there have been been multiple cases of people who've been pulled out of extremely cold water or found outside in sub-zero temperatures, seemingly dead. They're cold, stiff, blue and without any vital signs. But despite appearances they're actually this trope due to hypothermia both causing, or at least contributing to, the lack of vitals and greatly extending the length of time that the brain can go without oxygen. Many of the individuals in question have gone on to make full recoveries after being warmed up and resuscitated. This is why there is an adage in medicine that goes, theyre not dead until theyre warm and dead. 
- Suspended animation is the temporary (short- or long-term) slowing or stopping of biological function so that physiological capabilities are preserved. 
- DHCA is a surgical technique that induces deep medical hypothermia. It's used when blood circulation to the brain must be stopped because of delicate surgery within the brain, or because of surgery on large blood vessels that lead to or from the brain. It's is a form of carefully managed clinical death in which heartbeat, breathing and all brain activity cease. 
- EPR is an emergency procedure to save dying patients with traumatic injuries. The blood will be replaced with a cold saline solution, which stops cellular activity. There is no heartbeat, no breathing and no brain activity. At this point, the patient is technically dead. But the cells will stay alive, working at a much slower pace at the lower temperature. This gives doctors more time to fix the injury. The patients can be returned to life by replacing the saline with blood. 
- Scientists hope to create a drug that induces suspended animation (pill or injection).
- Cryonics patients. They arrange to be frozen after death, in the hopes that future technology will bring them back to life.