Hell on Earth, literally.
In most cases, Hell is something you don't have to worry about unless you're on the negative side of the Karma Meter, and even then, only if you're careless enough to die. Even if it's more tangible, it's usually on the other side of a Hell Gate which can be handily sealed up if necessary at a maximum of a few thousand human sacrifices to the dark ones. Then there are the unlucky worlds which have the ultimate in Crapsack Worlds in their backyards.
Usually deep underground, occupied by the physical Legions of Hell and probably making themselves felt on the human lands above them. In particularly bad cases they may be unstoppable, and the only hope is to avoid disturbing them in the first place. In more optimistic settings, some heroes may find themselves completely occupied keeping the demons at bay and stopping them from ravaging their fellow humans. Should they manage to fight the demons off, only the truly mightiest of heroes can actually take the step of invading hell, and most won't be the most stable individuals after the experience.
If the humans are lucky, heaven will also have set up shop in the region. If they're even luckier, the hapless monkeys won't end up caught in the supernatural crossfire.
Hell on Earth is when Hell was originally in another dimension, but is deciding to colonise the physical realm and create this situation. Or just kill everyone; demons are fickle like that. Mordor is related — a dark physical realm which is like hell but often isn't explicitly said or even meant to be hell, just an inherently evil land.
- Magic: The Gathering:
- While not called "Hell", Phyrexia is pretty close. It was a series of nine spheres nested inside each other, each with a different purpose. The Ninth Sphere was the abode of Yawgmoth ("The Ineffable" to the Phyrexians) the Machine-God. This construction is an obvious homage to Dante's Inferno. The fact that it was a perversion of nature, drenched in soot, and the high-ranking Phyrexians were referred to as "Demons" only drives this point home. Cards like Priest of Gix imply that there was even a Religion of Evil worshiping Yawgmoth in the main storyline world of Dominaria.
- The planar shard of Grixis is also pretty close. It's defined by the lack of White and Green mana, the sources of light and life. Grixis is ruled by demons, the dead, and worse, all vying for ever dwindling amounts of life energy which is also constantly being recycled. Life there sucks for pretty much everybody but it really sucks for the few remaining mortal residents.
- Dark Angel: The Ascent: Hell is portrayed this way. The demonic heroine only has to go through a tunnel to crawl out of the sewers in a human city.
- In Bedazzled (1967), the Devil and George materialize in a grim, vacant city neighborhood that hadn't rebuilt from the Blitz. George wonders if it's Hell; the Devil tells him it's his London branch, pointing to his HQ, a sleazy-looking little basement nightclub.
- In Bedazzled (2000), the Devil takes Elliot to a Los Angeles nightclub where everyone is partying and having a great time, and welcome Elliot with open arms; the Devil later says she has offices in Hell, Purgatory and L.A., so this is presumably her L.A. branch. Near the end of the movie Elliot returns, and the party is still going on, and he notices that everyone seems to be enjoying it less than before.
- The Divine Comedy: To show the struggle against sin and evil in a cohesive narrative, the narrative features the protagonist entering Hell through a series of caves.
- In The Descent by Jeff Long, it turns out that there's an underground world under ours, inhabited by cruel demon-like humanoids. There's also a Satan... of sorts.
- The Cosmere:
- In The Stormlight Archive, Hell is called Damnation and characters refer to it the same way we do. But hints in the text and Word of God indicate that Damnation is actually a planet called Braize, ruled by Odium. It is presumably the source of the Voidspren, as well as the location where the Heralds were tortured between Desolations.
- Shadows for Silence in the Forests of Hell: A continent on a minor shardworld is entirely occupied by what appear to be shades of the dead. Exactly what relation they have to the original person is unclear, but they are malevolent and don't seem very happy. Notably people came here from somewhere else fleeing something known only as "the Evil", which was apparently so bad that the murderous shades of the dead were an improvement.
- Harlan Ellison gives us I Have No Mouth, and I Must Scream, where all of humanity has been annihilated by a god-like supercomputer save for an unlucky five, who are tortured for eternity to give the machine purpose and satisfaction.
- Tolkien's Legendarium: Utumno, Melkor's first fortress and base of operations, located in the far north of Middle-earth. It was the place where he corrupted Elves to become the first Orcs. As a side note, utumno literally means "hell" in Quenya (its cognate in Sindarin is udûn, which survives as a placename in Mordor).
- Lexx: Hell is a literal planet called Fire, which all damned from the Light and Dark Universe are sent to upon their deaths.
- The Book of Revelation describes Hell in physical terms as "the Lake of Fire," where the Devil and all who follow him are thrown into when God makes his Last Judgement. Since the aftermath of the Last Judgement sees the Earth return to the paradise before man fell into evil, it makes sense that this now physical Heaven would be contrasted with a physical Hell.
- Greek mythology has Hadesnote , which is occasionally depicted as an actual physical location accessible via various caves. The Greeks believed certain actual caves led to the underworld because of the noxious volcanic fumes issuing out of them.
- Thomas Hobbes was a materialist but was weary of being accused of atheism and believed in physical everything. Democritus said if matter is eternally conserved, then any combination of them will eventually be repeated — therefore the Resurrection. Physical heaven, hell, God, they're all out there somewhere.
- Japanese netherworld used to be accessible via a cavern which was sealed shut by Izanagi after he escaped his deceased wife's wrath.
- The Mayans also believed the underworld was accessible via a certain cave.
- In Guatuso mythology, the souls of people who die from a snakebite go to the place of punishment located somewhere along the lower course of the Río Frío (Costa Rica) and is said to be aboveground.
- The Binding of Isaac: Satan's domain, named Sheol, exists physically in the in-game world, accessed by the same trap doors that lead down from one floor to another. It is possible to reach it by using a shovel.
- Diablo's titular archdemon ends up creating a physical hell from the dreams of the luckless prince Albrecht, it being a separate dimension originally. All the games have you heading into Hell at some point to carry out your mission — in Diablo II, you head there to destroy Diablo and undo the mistake of the hero of the first Diablo, while in Diablo III, you head there to close the rifts that are allowing Diablo's forces to invade Heaven.
- Dwarf Fortress: It is possible to dig to hell. Just don't expect to win when you arrive; hell has a population that is either in the billions or infinite, and some of the demons don't have organs, so you literally cannot kill them. As players have found out, using the dwarven way of acting completely insane, it's definitely possible to win the fight. And then colonize the place.
- Princess Maker 2 has a physical hell complete with its legions, though it appears to be under heaven's jurisdiction.
- Fall from Heaven starts with a real, physical Hell, sealed away so nobody can get to it without being damned, and according to the Compact, it should stay that way. If, however, the Sheam and the Ashen Veil get their way, that can is coming open, Hyborem is coming out, and the Infernals are going to start trying to bring about hell on Erebus as possibly the scariest faction in the game.
- Disgaea: Hour of Darkness: While sinful humans have their souls carted off to the Netherworld after dying, the EDF on Earth found a way to travel there in spaceships using warp speed travel. Vulcanus might have told them how.
- The original trilogy's entire plot revolves around the idea that teleportation experiments on Mars resulted in portals to hell itself, cue The Marine. Also, the Martians already did the same thing by accident long ago, sacrificed most of their civilisation to fix it and fled to Earth.
- Doom Eternal fleshes out hell's true nature and history: it's located in Another Dimension, but it was originally no different from any other of the myriad dimensions created by The Father. In fact, it was originally called Jekkad and was a paradise. It was only after it fell to corruption and was cut off from everywhere else for eons due to the original Father's betrayal by the Makyrs and his subsequent rage which resulted in him becoming the Dark Lord and his people becoming the original demons that it became what it is now.
- Scribblenauts: Just as how you can summon schools and museums you can actually summon Hell. Interacting with it produces a demon. Physical Heaven also exists.
- Touhou Project: Gensokyo used to have at least one of the many hells, the Hell of Blazing Fires, located beneath the ground. All you had to do was enter the cave known as the Dark Blowhole, pass over the forgotten bridge, and through the Palace of Earth Spirits. At some point though it was relocated and it's not exactly clear where.
- In Terraria, you can actually enter Hell (called the Underworld ingame) simply by digging down deep enough. In there you'll find demons, a wall of flesh, and bats. There's lava, fire, imps, lava slimes, hellbats, lava, fire, and lava. It's dangerous down there. Yet ironically much safer than the overworld once Hard Mode kicks in as unspeakable horrors once sealed in the form of the Wall of Flesh are released.
- Nexus Clash: One iteration of the franchise allowed demonic player characters to pour energy into the land of the mortal plane and transform buildings and terrain into their Fire and Brimstone Hell equivalents. Angels could do the same to try to turn it into Physical Heaven instead.
- Futurama has a physical hell for robots, complete with a robot devil. It's built beneath an abandoned theme park in New Jersey.