In real life, proper treatment of the dead is a matter of respect and hygiene (rotting corpses leave a terrible mess). In fiction, the recently dead can be significantly more dangerous.
The most common variation of this trope has the recently dead come back as The Undead, either in the classic sense of zombies and ghosts, or mutating into more horrifying beasties. The danger can also be more external, with risks like corpses attracting monsters (much as our ancestors might have feared a corpse attracting a hungry predator) or spreading disease (as often happens during epidemics). Sometimes the danger comes from the risk of the dead being misused (such as the local Necromancer casting Animate Dead on every corpse they can find).
Prevention can be as simple as performing proper funeral rites to prevent the dead coming back to haunt the living. Or even (especially in more science fiction-y settings), just making sure the corpse is properly destroyed (often via Fire Keeps It Dead). It's also not unheard of for a setting to split the difference, and make a setting's funerary rituals the result of the correct procedure for disposing of the dead. Of course "simple" is relative; you can expect a Forbidden Zone which was abandoned after too many people died at once to do anything about it.
Many Zombie Apocalypse settings have a subtrope, where any fresh corpse will soon rise and join the undead horde (making anyone close to death a Zombie Infectee). If this is a game mechanic, expect a Reviving Enemy. Compare Anti-Regeneration, for preventing a still living monster from healing itself. This may overlap with Unfinished Business, if the reason a ghost may come back is because its remains weren't properly dealt with.
Not to be confused with simply hiding or destroying a body for other reasons (like covering up the fact someone died), which falls under Disposing of a Body, or already dangerous creatures which need to be made Deader Than Dead.
- Dungeon Keeper Ami: Worshippers of Crowned Death have the ability to animate relatively intact corpses in their area of influence. So, while facing one, Ami had to rapidly cut up the single corpse in her territory. The oldest dragon.
- In Kingdom of Heaven, there's a more mundane example near the end of the film. It becomes necessary to cremate the bodies of people who died in battle rather than giving them a proper burial because otherwise everyone else would die of disease in days.
- In Land of the Dead, everybody becomes a zombie when they die (unless they're shot in the head), so one of Cholo's jobs is to dispose of the recently-deceased; in the director's cut a man who hanged himself turns into a zombie, and Cholo is sent to deal with it.
- Night of the Living Dead (1968) ia a Trope Codifier - in the film, a news broadcast directs the viewers to drag any corpse out into the street and burn it lest they rise up as a "flesh eating ghoul".
- In the Old Kingdom series by Garth Nix, dead bodies are disposed of by cremation because any intact corpse is a risk to become an undead monster of some kind (either reoccupied by a dead spirit that refuses to go on to the afterlife, or reanimated as a servant by a necromancer).
- In The Blood Ladders: The Church practices cremation due to a historical demonic incursion that possessed corpses. There's a new one in the third book.
- A Song of Ice and Fire: The Wildlings burn the dead to prevent them from being resurrected as wights by the Others.
- World War Z: Even after a zombie has been dispatched, the body is still a threat, due to the Solanum in its system. Those tasked with disposing of the bodies often wear gloves and masks to avoid being infected.
- One of the "recorded attacks" in The Zombie Survival Guide proposes the risk of corpses reanimating as the reason why the ancient Egyptians removed the brains of their mummies.
- Secret Histories: The Drood Ancient Order of Protectors teleports its dead into the sun, both to protect them from enemy Necromancy and because its membership tends to be strong-willed, ornery, and prone to haunting over Unfinished Business.
- Galaxy of Fear: The planet Necropolis is said to be Cursed by an ancient Necromancer, forcing people to pay Due to the Dead or suffer their vengeful return, so they have massive gated cemetaries and rigid burial customs. Zombies do start to show up when outsiders trespass on the cemetary, due to a Mad Doctor experimenting with a "cure for death".
- In the Christopher Anvil story "Star Tiger", the lifeforms on Bemus III are Asteroids Monsters that, if killed, regenerate if the corpse isn't completely destroyed. The solution eventually arrived at is to keep the bodies underwater; even if they do regenerate, they just drown again.
- In the Chernobyl episode "Open Wide, O Earth", three firefighters who died from Acute Radiation Sickness were buried in lead-lined caskets, sealed in zinc covered coffins, and covered in concrete. Because it is too dangerous for them to be cremated or given a proper burial, due to the high risk of contamination from the radiation which killed them.
- In Lost, those who live on the island (Others and, later, Dharma people) insist on burying their dead, no matter what the circumstances. The Losties later learn that the Smoke Monster can take the form of those who are dead if they haven't been buried.
- In Pose, taking place amid the AIDS crisis, patients who succumb to the disease get buried in a plain box in a remote section of Hart Island, by undertakers wearing hazmat suits, because at the time, it was still believed that the virus could become airborne.
- In Supernatural, Hunters must burn a body and anything strongly associated with the person in order to either destroy an existing ghost causing problems or, as a precaution, to keep one from forming. When done for fallen comrades, this is called a Hunter's Funeral.
- In some versions of Norse paganism a Viking Funeral was necessary for the spirit to depart, else the corpse might rise as a Draugr and torment its family. In places where lumber was scarce, like Iceland, cremation was only practical for the upper classes and others resorted to elaborate rituals to confuse the Draugr like knocking out walls to carry the corpse out, tying the big toes together, burying it upside down, or laying an open pair of scissors on its' chest.
- Maschalismos is the real-world zontanecrological practice of preparing a corpse so that it can't rise from the dead.
- In Blades in the Dark, everyone comes back as a ghost 1-3 days after death. Since the mere presence of a ghost has nasty supernatural effects on the living, every human corpse has to be dissolved in boiling electroplasm within that time to prevent the ghost from leaving it. The Order of Spirit Wardens provides this public service in Duskwall and has magical means of detecting any new dead bodies within the city walls, therefore players are discouraged from killing NPCs, as getting the Wardens involved always raises their Wanted Meter faster.
- In Final Fantasy X anyone who dies (especially in the wake of Sin's attacks) needs to have their soul sent to the farplane by a summoner, or they'll eventually begin to hate humanity and turn into a fiend (i.e., the Random Encounter monsters). The exceptions being Unsent; strong willed individuals who can hang on to their human forms (often with some purpose in mind).
- In Death Stranding, monsters called BTs roam the Earth. Anyone who dies turns into one around 48 hours later. If they eat a person it causes an Anti Matter explosion. Live people cause city destroying explosions and dead bodies cause smaller, but still devastating ones. Repatriates, like Sam, cause small explosions. It's heavily implied that the initial wave of deaths/explosions more or less wiped out most populated areas. The only solution is to incinerate corpses as soon as possible (with nobody present but the courier team who brought them to the crematorium). This also serves as a gameplay mechanic; should Sam Bridges get eaten by a BT, the explosion leaves a permanent crater in the game world. If an NPC gets eaten you have to go back to an earlier save. If you kill an NPC, you are expected to bring their corpse to an incinerator and are docked "likes" if you don't.
- In Resident Evil, the T-virus can still resurrect the recently dead during an outbreak. In particular, the remake of the first game had zombies become Crimson Heads if their corpses weren't destroyed.
- At the start of Diablo III, New Tristram, which is under siege by the undead, is starting to burn their dead to keep them from rising as more undead.
- In Dwarf Fortress, corpses not given a proper burial will spawn a ghost to haunt the area. What that ghost will do ranges from generic haunting shennanigans to organizing their own Wake.
- In the Dragon Age setting, dead bodies are easily possessed by demons, so most funerals involve the destruction of the body. This is usually done by cremation, although the Avvar bring their bodies to mountain tops to be eaten by carrion birds. The notable exception is the nation of Nevarra, which has massive necropoli with all of their dead entombed. They have necromancers that summon benign spirits to inhabit the bodies so they don't get possessed.
- In Halo 2's and Halo 3's levels with the Flood, corpses of dead Flood victims can be sliced up or smashed to prevent them from resurrecting should more Flood pod infectors possess them. This only works on prior Flood victims; bodies that haven't been infected yet cannot be destroyed.
- In The Elder Scrolls Online, Argonians in Murkmire put a grave-stake through the body of the dead to keep them from rising as a bog blight (essentially a zombie).
- Played for laughs in Family Guy, where the mayor requires all corpses to be encased in concrete before burial to eliminate the possibility it might rise as a zombie.