The following is a list of fiction employing parallel universes or alternate realities
- Margaret Cavendish, Duchess of Newcastle, wrote The Blazing World (1666), a book far ahead of its time, in which the heroine passes through a portal near the North Pole to a world with different stars in the sky and talking animals. Although Cavendish never came up with the idea of a multiverse, she did have the idea of a single alternate world down pat.
- Edwin A. Abbott, mathematician and theologian, wrote Flatland (1886), also known as "Flatland: A Romance of Many Dimensions." It recounts the story of a two-dimensional world inhabited by living geometric figures: triangles, squares, circles, etc., and explores concepts of other dimensions (or universes) including Pointland, Lineland, and Spaceland. A feature film adaptation of this novella was made in 2007 called Flatland The Film.
- Murray Leinster's story "Sidewise in Time" (1933), showing different parts of the Earth somehow occupied by different parallel universes, was influential in science fiction.
- H. Beam Piper, the author of the Paratime series, wrote several stories dealing with alternate realities based on points of divergence far in the past. The stories are usually written from the perspective of a law-enforcement outfit from a parallel reality which is charged to protect the secret of temporal transposition.
- Fredric Brown's What Mad Universe recounts the adventures of a science-fiction editor of the late 1940s who is thrown into a parallel universe that reflects the fantasies of his most annoying letter-to-the-editor writer (an adolescent male, naturally).
- Isaac Asimov's novel The Gods Themselves depicts scientists in our universe who find a way to "import" small amounts of matter from a universe having different physical laws, with unforeseen consequences.
- K. A. Applegate's series, Everworld (1999-2001): Several teenagers travel into a parallel world occupied by the mythological beings of Earth.
- Stephen King's series The Dark Tower has doors that send travelers to different parallel Earths, or, as termed in the story, different levels of the Tower. King also frequently utilizes this idea in other stories, such as The Mist, From A Buick 8, The Talisman, Black House and Insomnia.
- Robert A. Heinlein's novel The Number of the Beast is focused around a 'time machine' that also proves to be able to travel sideways and other directions in time, allowing for crossing into other realities, even ones previously considered fictional by the protagonists.
- S. M. Stirling's novel Conquistador is based on travel between parallel universes, with a group of 20th century Americans having found a means to secretly colonize a world where civilization never advanced past the classical era.
- Globus Cassus is a book describing a utopian project for a universe contrary to ours, it describes an antipode to the 'real' world.
- The Wheel of Time by Robert Jordan series features not only one cyclic universe, but many. In one particular instance, Rand al'Thor's, the main protagonist's mind, is deluged by possibilities for his own life, and in all of these possibilities he dies before defeating the Dark One and is taunted by him a moment before death. Also in the Wheel of Time universe, Tel'aran'rhiod, the world of dreams, is said to touch this world and also many other worlds. Dreamers, those who walk the dream and can control the world of dreams to some extent, can go to a place where they see a vast darkness filled with countless pinpricks of light. These pinpricks of light are said to represent not only the dreams of those sleeping in this world but also the dreams of sleepers from other parallel worlds. Some of these parallel worlds are called Mirror Worlds, and represent what could have been had various events in history happened in different ways. Mirror Worlds can be physically visited through the use of a device called a Portal Stone, but the less likely the existence of the Mirror World was the less substantial and real it felt to the visitor.
- Diana Wynne Jones' Chrestomanci series revolves around the duty of the Chrestomanci to regulate magic in the twelve related worlds. These worlds have alternate histories, in which some people may exist only in a few worlds. It is necessary that the Chrestomanci must exist in only one, because this gives him the nine lives needed for his role. Other works of Jones' that include parallel universes: The Magid series; Deep Secret and the The Merlin Conspiracy in which the multiverse is shaped like an infinity sign and contains Ayewards and Naywards. The Derkholm series: Dark Lord of Derkholm and its sequel Year of the Griffin in which Pilgrims come from a parallel world for Mr. Chesney's offworld tours. In Howl's Moving Castle, though it does not play a major part in the plot, the wizard Howl is actually from our world. In A Tale of Time City, the main character, Vivian, is kidnapped and taken to Time City, a city out of time and space. Along with her new friends and past kidnappers Jonathan and Sam, she hunts through time and space for the polarites that are gradually being stolen. In A Sudden Wild Magic a group of benevolent witches set out to stop the magicians of Arth who steal ideas, technology, and innovations from Earth. In Hexwood, the machine Bannus sucks potential Reigners from all over the universe into the Wood. In The Homeward Bounders Jamie is made into a Homeward Bounder by "Them" which means he must constantly travel from world to world until he finds his home again.
- John DeChancie's Castle Perilous series tells of a huge magical castle containing portals to 144,000 worlds, including Earth.
- Stephen R. Donaldson's Mordant's Need series, which includes The Mirror of Her Dreams and A Man Rides Through, follows a heroine who can pass into another world through mirrors.
- In The Chronicles of Thomas Covenant series, also by Stephen R. Donaldson, main character Thomas Covanent is transported to another world called The Land. Each time he travels to The Land corresponds to an injury in the real world that leaves him unconscious. While in The Land, time travels differently then in our world. Where a year may be spent in The Land, mere minutes will have passed on Earth. In The Land there is great power and magic wielded by the Lords of Revelstone, the rulers of The Land, who fight against The Land's ancient enemy, Lord Foul. Lord Foul was imprisoned in the Land by the Creator after corrupting the Land during its creation. He constantly seeks to use Covanent's Wild Magic in order to break the Arch of Time and gain his freedom. In the First Chronicles, Covenant finds another man, Hile Troy, from his world who has entered the Land. Troy worked for the Defense Department for the United States, and employed his knowledge in leading the armies of the Land against Foul. In the Second and Last Chronicles, he is accidentally accompanied to the Land by a doctor, Linden Avery. Linden is forced to accept what Covenant tells her about the Land, as she has never been there before.
- H. G. Wells wrote what is apparently the first explicit paratime novel, Men Like Gods (1923), complete with a multiverse theory and a paratime machine.
- In C. S. Lewis' classic Chronicles of Narnia series (1950-1956) children come and go between our world and Narnia, a land populated by talking animals. In The Magician's Nephew the Wood between the Worlds gives access to several worlds. In The Last Battle it transpires that all the worlds are joined together by a form of heaven.
- Phillip Pullman's His Dark Materials series (1995-2000) deals with two children who wander through multiple worlds, opening and closing windows between them. The final book elaborates the same idea (as C.S. Lewis') that all the worlds share a common heaven, and in this case, underworld.
- Jasper Fforde's Thursday Next series is set in a parallel universe which is very similar to ours but has (amusingly) different history. For example Britain and Russia are still fighting the Crimean War in 1985. As the story develops, the world of fiction also emerges as another parallel universe and the characters learn how to move between them.
- In L. Neil Smith's The Probability Broach series of novels characters from several different universes end up in one universe where American history took a different turn in the aftermath of the Revolution, with Albert Gallatin assisting the western Pennsylvania farmers of the Whiskey Rebellion, which culminates in George Washington's execution and the rise of a libertarian republic under a revised Articles of Confederation.
- In James P. Hogan's Paths to Otherwhere(1996), scientists at the Los Alamos Laboratory create a machine QUADAR which allow them to swap conscious with people in parallel universes. They explore various parallel universes.
- In Kia Asamiya's manga novel Space Battleship Nadesico, written alongside the series Martian Successor Nadesico but altering severely as the course of the story runs, the Jupiterians that are attacking Earth come from a parallel universe, the portal of which is in the red storm visible on Jupiter as a red spot. In their world, Japan won World War II, and because of their strong religious Shinto beliefs, their Gods did not die out, and they were able to use this magic to help strengthen their technology. However, their sun died out prematurely, and so they have come to our world to steal the energy from our sun to save their world.
- Sergey Lukyanenko's novel Rough Draft (2005) takes place across the multiverse of at least 22 worlds (it was implied that there were actually more worlds that haven't been discovered yet) linked together by a series of tower-like transfer points.
- I, Q is a 2000 Star Trek novel by Peter David and John de Lancie in which God attempts to destroy the multiverse in a large multi-universe maelstrom which the protagonists attempt to stop from within a newly created universe caused by the maelstrom.
- In D. J. MacHale's The Pendragon Adventure series there are ten different parallel universes (including our own), called territories, that are part of Halla, which is described as being every time and place that ever existed. Certain people, called Travelers, are able to go between the territories through portals known as Flumes. It is claimed that by traveling through a Flume, Travelers land on their destination territory exactly when they need to be there, suggesting time travel.
- In Robert J Sawyer's Neanderthal Parallax series (2003) a parallel historical universe exists in which it was Neanderthals not Homo sapiens who survived to become the dominant species. In a quantum physics experiment gone wrong a Neanderthal scientist is accidentally transported into the universe of Homo sapiens. Eventually a portal between the two universes is established and travelling to an alternate universe becomes a controlled event.
- Michael Lawrence's The Aldous Lexicon (2005-2007), comprising A Crack in the Line, Small Eternities and The Underwood See, concerns comings and goings between initially two, later many parallel realities.
- In The Man Who Folded Himself (1973) by David Gerrold, paradoxes caused by time travel result in the creation of multiple universes.
- In Mirror Dreams (2002) and Mirror Wakes (2003) by Catherine Webb, there are mirror universes, one a magical universe where technology barely works, the other a scientific universe where magic barely works. The inhabitants can physically visit each other's worlds in dreams.
- In the Stravaganza series by Mary Hoffman various people travel between present-day England and an alternative, somewhat magical Renaissance Italy called Talia.
- In the Alastair Reynolds novel Absolution Gap, a race called the "Shadows" drives the action. They claim to be from a parallel universe which has been overrun by a rogue terraforming system that has destroyed their entire universe. They have sent instructions to our world on how to build machinery to let them across. The characters eventually decide not to do so as a race which tried previously was wiped out by alien races aimed at stopping the Shadows. It is implied at the end that the Shadows are in fact from a future version of our own universe.
- In The Divide trilogy by Elizabeth Kay Felix Sanders crosses into a parallel universe where magic and magical beings exist while science and human beings are considered mythical.
- Andrew Crumey's novel Mobius Dick features a parallel world in which Nazi Germany invaded Britain, the works of Thomas Mann were written by another novelist named Behring, and Erwin Schrodinger failed to find the quantum theory equation that bears his name. The parallel worlds become connected due to experiments with quantum computers.
- In Darren Shan's Demonata series a boy can open windows to parallel worlds with his hands. A part of the story also plays in one of these parallel worlds, the Demonata.
- Harry Turtledove's Crosstime Traffic series of books by Harry Turtledove centers on an Earth that has discovered access to alternate universes where history went differently. "Crosstime Traffic" is the name of the company with a global monopoly on the technology.
- The Butterfly Effect, 2004, recounts the story of a young college student who can modify past occurrences in time and in effect, create different parallel universes for himself.
- The Parallel, a 1963 episode of The Twilight Zone written by Rod Serling, was one of the earliest examples of parallel universe as a key plot element on American television.
- The 1960s fantasy/horror soap opera Dark Shadows, which introduced the concept of "parallel time" when the main character, Barnabas, witnesses unexplainable changes in a closed off part of his family's house. During one of these changes, he becomes trapped for a time in a parallel world.
- Sliders dealt with a group of mostly-unwilling travellers who ended up "sliding" between various parallel Earths in an attempt to find their way back to their own universe. Plots included an Earth in which the population is controlled through a lottery, an Earth where most of the males were killed by germ warfare, an Earth where dinosaurs are still alive, and an Earth in which the population have been turned into flesh-eating zombies. According to a main character Quinn, there were an infinite number of universes where different single decisions were different and even a world where the Earth formed differently and rotated around the Sun slower, slowing down that timeline.
- Star Trek featured the recurring mirror universe, a dark reflection of the normal universe in which the regular characters are twisted, self-serving and more than willing to resort to murder. The mirror universe was introduced in the original Star Trek, and it also appeared in Enterprise, but was featured most often in Deep Space Nine.
- The original Doctor Who series occasionally featured parallel worlds. Examples include Inferno (1970), where Great Britain has been a republic since 1943 (the Royal Family having been executed) and is ruled by a totalitarian regime, and the 1980-1981 "E-space" trilogy of episodes (Full Circle, State of Decay, and Warriors' Gate). The second series of the 2005 revival of the show made frequent use of the concept beginning with "Rise of the Cybermen" and "The Age of Steel", postulating a parallel world where Britain also has republican status and is run by a President, Zeppelins patrol the sky, and an alternate race of Cybermen are created. Since the Time War, travel between parallel universes is supposedly near-impossible, but a breach between the universes makes frequent visits easy in the second series finale "Army of Ghosts"/"Doomsday". These visits cause increasing damage to the universes and the breach is permanently sealed.
- Joss Whedon's cult television series, Buffy the Vampire Slayer and Angel, have featured both parallel universes, such as Pylea, and alternate realities, such as one where most of the regular cast were either dead or vampires. Also mentioned, but never seen, is the hypothetical World Without Shrimp and the confirmed-real World With Nothing But Shrimp.
- In Joss Whedon's popular but short-lived cult series Firefly, the Universe is referred to as the 'Verse. In the 14th and last episode "Objects In Space", when River Tams' brother Dr. Simon Tam is threatened by bounty hunter Jubal Early he replies "I don't think my last act in this 'Verse (rather than saying the 'Verse ) is going to be betraying my sister."
- The anime Digimon features an alternative perceived reality called the Digital World. The Digital World is created as a result of the Earth's electronic network, with everything being made up of data instead of matter. Also, certain seasons, games, and manga are set in a different parallel Earth, with its own version of a Digital World.
- The final episode of the anime series Neon Genesis Evangelion presents the main character Shinji Ikari with an alternate universe, wherein the cataclysmic event Second Impact had not occurred and all the main characters live peaceful lives. This universe went on to be the basis for numerous spin-off series, including Neon Genesis Evangelion: Angelic Days. It is also stated in the episode that this universe was just one of many possible alternate universes.
- The show Stargate SG1 has had several episodes dealing with parallel universes. The first had Daniel Jackson finding a mirror looking device, known as the Quantum Mirror, where by touching the "mirror" he was taken to a parallel universe in which things hadn't gone so well compared to his reality. Another episode has a Samantha Carter and a character killed off in the second episode of the show come through the mirror to request help from the show's normal reality. With the end of that show the Quantum Mirror was destroyed. The next episode, "Ripple Effect", dealing with alternate realities has a lot of different SG1 teams coming through the same Gate. The latest episode, "The Road Not Taken", had Samantha Carter travel to an alternate reality where martial law was in effect.
- In Charmed, there exists an alternate dimension where all the evil are good and all the good are evil. The reason for this given that there has to be balance in the universe, so there can never be an area where everything is all good and one where it is all bad as this would affect the grand design of life. So for every good thing that the Charmed Ones do for good in this world, it is done for evil in another to keep things balanced. Mostly, everything occurs exactly the same way, mirroring the real world. Some differences are that all Whitelighters are Darklighters and vice versa, and that The Underworld is a Garden of Eden-like paradise. The Demon of Fear is the Demon of Hope, and Wyatt Halliwell faces a future in which he turns good one day as opposed to one where he turns evil. Some figures, such as the morally ambiguous Gideon, remain largely similar.
- In the The Jimmy Timmy Power Hour TV series, the main characters move back and forth from the respective universes of The Fairly Oddparents and The Adventures of Jimmy Neutron: Boy Genius.
- In the Smallville episode 'Reckoning' Lana Lang is killed in a car crash while being chased by Lex Luthor. Clark Kent journeys to his Fortress of Solitude where he uses a Kryptonian crystal to go back in time and save Lana (creating an alternate timeline to the original events), however the universe 'finds a balance' and Clark's father Johnathan Kent dies instead.
- The anime Buraku Burondo also uses multiple dimensions (parallel universes) as part of its storyline. Most main characters all come from other universes, but end up in the same.
- The anime Rockman EXE Beast involves another dimension parallel to Earth named Beyondard, in which there are parallel versions of the characters in the world, where a war between the antagonists Falzer and Greiga are fighting over control, as well as the Synchronizer, Trill. Many Navis from Earth are in this world serving as the lower antagonists for the series, preferring to be called 'Zoanaroids' (strangely, many of the Zoanaroids were already deleted on Earth--a concept used by Full Metal Alchemist: Conqueror of Shamballa), then their real name. These Navis had special forms that gave them increased strength and an altered appearance. In this world, a Navi could be materialized within Beyondard without the need of a dimensional area, due to its strange environment caused by an accident. The environment would also cause those using Cross Fusion pain while merged.
- The SiFi Charlie Jade made by Canada and South Africa, shot in South Africa: It describes 3 parallel universes that are Alphaverse, Betaverse, Gammaverse.
- The BBC TV Series, Red Dwarf offers several humorous takes on the concept that don't involve an evil twin joke, including one episode where women are the dominant gender (Nellie Armstrong was the first person on the moon, and Wilma Shakespeare wrote great plays such as Rachel III and The Taming of the Shrimp), and another where Arnold Rimmer becomes the far more dashing and debonaire Ace Rimmer.
- Lastly, a more recent example would be on the episode "The Chrismukkah-huh?" of The O.C., in which characters Taylor Townsend and Ryan Atwood venture into a parallel universe in which they never existed, in order to set things straight to get back to their own world.
- Fifth Dimension is a radio drama adaption of the short story, "The Plattner Story" by H. G. Wells. A chemistry teacher is accidentally thrust into a parallel world with alien inhabitants. The regular world continues to be visible, though translucent and intangible.
- Undone is a radio comedy based ont he idea of parallel versions of London, in particular "Undone". Undone is seen as a place where weirdness is normal, while mundaneness is normal in London, with some "Leakage" between the two. There is also a third version called "Donlon", a more mundane version of London in which everything is generic.
- The main character in François Schuiten and Benoît Peeters' comic book L'enfant penchée lives on our Earth, but comes from a parallel universe. She is attached to this other universe's gravitational pull and therefore stands inclined.
- The Caste of the Metabarons comics by Alejandro Jodorowsky features two wars between our universe and alternate ones.
- In Zenith: Phase Three, superheroes from many parallel universes must band together to defend their worlds.
- The British comic book series The Adventures of Luther Arkwright is based around the concept of parallel universes.
- in Yu-Gi-Oh's English version, "Shadow Games" happen in an Alternate Reality, known as the "Shadow Realm".
- Alternate universes are often used as an explanation for crossovers between different companies' characters.
- Ultimate Marvel is a new reinvisioning of the Marvel Universe, taking place in a different universe (Earth-1610) to the mainstream Earth-616. Similarly, other retellings such as Spider-Man: India and the Marvel Mangaverse take place in alternate universes.
- The Marvel Comics series Exiles details the adventures of a dimension-hopping band of superheroes from other alternate universes in the Marvel Multiverse.
- Jenny Everywhere is an open source webcomic character, being able to 'shift' between realities. Each universe has its own Jenny Everywhere, so she is literally everywhere (that implies other living persons being solely unique). In some stories Everywheres from different universes will meet each other.
- The DC Comics has had two major events, the Crisis on Infinite Earths and Infinite Crisis, which both heavily revolved around the alternate universes in the DC Multiverse. Although the Multiverse was officially destroyed during the Crisis on Infinite Earths, DC continued to publish a number of non-continuity stories under the Elseworlds banner, telling stories of DC characters in universes with significant differences from the main DC continuity. For example, Superman: Red Son depicted a world where Superman's spaceship landed not in Kansas, but in the Soviet Union.
- Skobek Universe which houses Toadafrog from Green Frog Studios's comics, which is connected to the actual universe through a wormhole, which is how countries like Korea, Greenland, species like the Human, and concepts such as rock music, classical music, baseball, and the cinema come from.
- The science-fiction series Bucky O'Hare is set in a parallel universe known as the Aniverse, where all inhabitants are anthropomorphic animals.
- +Anima by Natsumi Mukai The story is about four anthropomorphic characters; outcasts who are searching for others of their kind. Despite its popularity, the manga ended on its tenth volume.
- The Dungeons & Dragons role-playing game has a thoroughly developed system of planes of existence. A popular campaign setting for the game, Planescape, centers around travelling between these planes. Ravenloft, a gothic horror setting for Dungeons & Dragons, is based entirely in a single demiplane.
- GURPS Infinite Worlds, a supplement for the Fourth Edition of the GURPS role-playing game, expands upon the campaign setting of conflict between the Infinity Patrol, which is the time-travel agency on "our" Earth, referred to as Homeline, and Centrum across a multiplicity of alternate history Earths. It won the 2005 Origins Award as Best Game Supplement.
- In the computer game Myst a people known as D'ni colonized Earth from another universe, and kept traveling to other universes (known as Ages) through Linking Books. According to their cosmology, each universe is a leaf of the Terokh Jeruth, the Tree of Possibilities. Myst also includes the use of Trap Books as empty universes for storing criminals, although they were later retconned to be complete universes of their own, called Prison Ages.
- The video game Metroid Prime 2: Echoes features the planet Aether, which is struck by a meteor. The strange, energetic substance (called Phazon) within the meteor, along with the force of the impact, split the planet's reality into light and dark dimensions. Samus, the heroine, must travel between the two dimensions, transferring energy back to the light dimension before the two competing worlds destroy one another.
- At one point in the video game Crash Twinsanity, the main protagonists (Crash Bandicoot and Doctor Neo Cortex) travel to the mysterious 10th Dimension, where everything that is good in their dimension is evil, and vice versa.
- In the video game Chrono Cross (2001), the main character must travel between two dimensions, known as "Home World" (the world from which the main character originates) and "Another World".
- In the video game Star Ocean: Till the End of Time the characters unknowingly live in a "video game" created by people in another universe called 4D Space. Eventually, the creators of the game see fit to reboot the game server, effectively destroying the universe in the process, however, once the process is complete, the characters find the universe as they know it intact, and all links to 4D space inaccessible. Suggesting that by destroying the universe, contact between the two planes of existence was severed, without resulting in the destruction of either plane.
- In the Spyro the Dragon series, an evil sorcerer sends all of the inhabitants of the three realms to their Shadow Realm counterparts, leaving the normal realms empty save for Spyro.
- The video game The Longest Journey features a story about two parallel universes, Stark and Arcadia. Stark is a futuristic universe with cyberpunk influences, while Arcadia is a fantastic medieval world.
- So far, six games in The Legend of Zelda series include alternate realities: A Link to the Past and The Legend of Zelda: Four Swords Adventures include an alternate "Dark World" along with the normal "light" one, and Majora's Mask is set in a parallel reality of Hyrule, Termina. Other games feature the same world in two different time periods. In Legend of Zelda: Twilight Princess there is a Twilight Realm where Link becomes a Wolf. In Link's Awakening there exists a kind of alternate universe inside the unconscious, dream state mind of the Wind Fish. There is also a parallel universe in Phantom Hourglass simply called the "World of the Ocean King" by the spirits.
- The Mortal Kombat series features a massive war between realities, known as "Realms of Mortal Kombat".
- In Final Fantasy X, Tidus is transported from his hometown of Zanarkand into Spira, a land where everything is radically different to him. The other characters explain various things to him, and these explanations are actually aimed at the player. As the game progresses, he finds that Zanarkand was destroyed 1,000 years before the start of the game, and the Zanarkand he is from is a just a dream created by the Fayth, the souls of those who died when the city perished.
- The Half-Life series features a number of parallel universes from which both hostile and friendly alien species originate. One inter-dimensional alien race, the Combine, conquers Earth and attempts to harvest and enslave humanity. Only in Half-Life and its expansion packs, however, does the player ever visit one of these parallel dimensions; the so-called 'border world', Xen.
- The real-time strategy ParaWorld is set in a parallel dimension discovered by a group of scientists in the 19th century. This new world is periodically connected to ours via natural gateways. In order to cross into that world, one must predict the exact time and location of the opening rift. ParaWorld is a world where electricity does not and cannot exist, and the word "lightning" is foreign to the natives. As such, technology has not gone beyond steam engines. Most tribes, however, prefer to utilize other means of transportation and warfare - dinosaurs. As discovered by three modern-day scientists who are trapped in ParaWorld, dinosaurs never existed on our Earth, and all the bones found by archaeologists have somehow crossed over through the portals. In ParaWorld, however, they exist alongside human tribes, some of which are similar culturally to ours (e.g. Norsemen, Dustriders (Beduins), and Dragon Clans (East Asia)).
- In Tales of Symphonia the two world exist next to each other without knowing of the other's existence. The two worlds unconsciously battle for control of the energy the worlds share, something like Metroid Prime 2: Echoes, except in that game, the two sides of the war know of each others existence and the energy they must share.
- The Silent Hill horror video game series incorporates a concept of parallel worlds that are related to main character's emotions, memories, fears and other projections of his or her subconsciousness. The most common distinction is between the normal world (as the world is seen in reality) and the evil world (as the world is seen when it is devoured by evil powers). Characters are switching (i.e. altering) between these two worlds numerous times during the game's plot. There is a number of ways in which a character may switch between the worlds (for example, he or she may experience a pounding headache and, after this event, he or she "wakes up" in the evil world). The architecture of the evil world (also referred as an alternative world) is basically the same as the one of the normal, "real" world (for instance, a hospital in the normal world has its equivalent in the evil world). However, images of the evil world demonstrate how the real world would look like if it would be devoured by evil powers (for example, a hospital in the real world is no longer a hospital in the evil world - it is in fact a decent torture block full of hellish images of pain and suffering).
- In Marathon Infinity a seemingly unstoppable creature, The W'rkncacnter, is unleashed, and the player must transport himself to different parallel realities until he finds the one in which he may prevent the release of the creature. In certain levels the player will appear before the release of the creature, and can then attempt to stop it. Every few levels, usually at the end of a chapter, the player would find himself in a surreal "dream world", in which his surroundings had little to no relation to the W'rkncacnter or even his original reality at all. It is suspected that these levels are not universes at all, but in fact a dreaming interlude before the player reaches his actual destination (this is debatable however since the player can be killed in these levels like any other). After the player succeeds in trapping the W'rkncacnter in a gigantic gravitational field, he is "freed" from the control of the artificial intelligences that had previously governed nearly every one of his objectives, and subsequently teleports to another reality, at which point the game ends. It is unknown what reality the player goes to next, but it is assumed that he is using his new freedom to explore various universes at his own leisure.
- The massively multiplayer online game Ultima Online used the parallel universe concept to rationalize the existence of multiple instances of the game world (called "shards"), so that players could be partitioned onto multiple servers for capacity reasons.