A Show Within a Show can be shockingly elaborate as the host series goes on, almost becoming a work in its own right.
Some writers would rather spend all that worldbuilding time creating new standalone works, but that doesn't mean that their characters in another work can just sit around watching blank screens.
Sometimes, a creator has two or more separate works of fiction that can't be part of the same universe, usually due to incompatible genres (e.g. a modern setting and Speculative Fiction), but one work could work as a work of fiction in the universe of another work. When a creator introduces one of their stories into one of their others as an In-Universe work of fiction, you get this trope.
This helps advertise the creator's other works, acting as a form of Product Placement for the creator.
Oftentimes the work being presented as fiction within fiction will be a different medium in the fictional universe, i.e. a film or tv series instead of a comic or book, which might be part of the creator's fantasy of getting their work adapted to a more "glamorous" medium. On the other hand, the characters might proclaim their creator's other work to be schlocky trash.
A Sub-Trope of Company Cross References. Contrast Canon Welding, when two works initially presented as separate are later established to be the same universe. Can be an example of Defictionalization if the reference to the work came before the creator produced it in real life.
Examples:
- Gosho Aoyama frequently cross-promotes his various manga series this way; maybe the best-known example is Ch. 2 of Case Closed, which features Vol. 1 of his first series Magic Kaito in the Kudos' library - long before the two series were kinda-sorta canon-welded into each other.
- Kujibiki♡Unbalance started as a Show Within a Show that the characters in Genshiken would often be seen reading the manga and cosplaying as. When Genshiken got an anime adaptation, clips for Kujibiki Unbalance were specifically made to be shown on televisions within the narrative, and those same clips would later be repurposed within its own anime adaptation.
- Monkey Punch: At one point in Lupin III: The Pursuit of Harimao's Treasure, Lupin is reading Transparent Gentleman, another work by Monkey Punch. Lupin even mentions the author by name.
- Masahiro Totsuka: In one episode of Bamboo Blade, Tamaki saves up money to buy the DVD Box sets of an anime called Material Puzzle. This is the title of a fantasy manga created by Masahiro Totsuka before Bamboo Blade, though it was never adapted into an anime IRL.
- Tsuburaya Productions: The 2018 anime SSSS.GRIDMAN and its sequel SSSS.DYNɅZENON treat the Ultra Series as an in-universe franchise, with characters owning merchandise, mentioning stage shows or otherwise referencing Ultraman media and characters as fictional.
- Miki Yoshikawa: In Yamada-kun and the Seven Witches, as an excuse to spend time with Shiraishi after school, Yamada starts dropping by a bookstore with her to buy volumes of the light novel series There's No Way This Bad Boy Would Fall For Ms. Four-Eyes!! by Mikihiko Yoshikawa, a play on Yoshikawa's earlier manga series Flunk Punk Rumblenote , with some differences in character design. Oddly, Flunk Punk Rumble's Daichi Shinagawa had previously made a cameo appearance, and the first appearance of the light novel came right after a crossover special between the two series, with the anime including other cameos of the characters.
- The h-mangaka Mahiro Ootori specializes in stories where a male protagonist acquires a harem of women where one of them acts as his preferred wife while the others are his concubines. His first major work My Harem in Another World references Tales of a Harem in Another World by another h-mangaka as an homage to the main character being "isekaied" into a video game and then acquiring a Cute Monster Girl harem, as well as a a human maid, before returning to his world with them. Ootori's later works then references My Harem in Another World as either a magical tome like in Slutty Elf Sisters Looking for a Husband, or as a sort of "how-to guide" for a couple who wants to experiment in the bedroom, like in My Wife Started Experimenting.
- Matt Groening: In The Simpsons Futurama Crossover Crisis The Simpsons exists as a comic book in the Futurama comics canon just as The Simpsons exists as a show in the Futurama series. — both are Matt Groening properties produced by his comic book label, Bongo Comics. The plot kicks off when the Brain Spawn return and trap the Planet Express crew inside one of Fry's issues of The Simpsons.
- The idea behind The Multiversity is that every universe in the DC Comics multiverse has comics that portray the events of other universes. For example, Mastermen shows Hitler reading an American Crusader comic, depicting the champion of Earth 8, while Pax Americana shows Captain Atom reading Ultra Comics, which depicts events in Earth 33.
- Pat Shand: In I Summoned Cthulhu to Fund My Kickstarter, Pat is trying to get people to buy Prophecy Lesbians, which is Shand's Destiny, NY in all but name.
- Disney: In 101 Dalmatians, Horace and Jasper are watching Springtime, a 1929 Silly Symphonies cartoon.
- Pixar: Toy Story 2: This trope is combined with Freeze-Frame Bonus. When the toys are flipping through the TV channels trying to find the commercial for Al's Toy Barn, the footage we see is from old Pixar shorts.
- Charlie Kaufman: At one point in Adaptation., Charlie is seen working on Being John Malkovich, for which he wrote the script.
- Ted Sikora: Apama - The Undiscovered Animal is a comic book supposedly created by David, the protagonist of the independent film Hero Tomorrow. Both were created by Ted Sikora. The comic also features a fictionalized version of Nothing Like Vaudeville, a musical that was also created by Sikora.
- Tom Six: Each of the sequels to The Human Centipede portray the previous film as being a work of fiction In-Universe, with the depraved acts depicted in the previous work inspiring the Villain Protagonist of the subsequent film. The alternate ending to the third film takes this into Mind Screw territory, with Dr. Heiter, the creator of the centipede from the original film, apparently ''dreaming the events of the third movie.
- Isaac Asimov's short story "Gold" is about efforts to adapt the second part of his novel The Gods Themselves into a holographic movie.
- Max Brooks: Although never mentioned specifically by name, The Zombie Survival Guide exists in Brooks' later novel World War Z. A couple characters refer to it in less than complimentary terms.
- Roald Dahl: Danny, the Champion of the World: Zigzagged. Danny's father tells him The BFG like it's a story, but he also claims to have met the BFG. However, he says it in a joking sort of way.
- Philip K. Dick: VALIS: At one point, the characters become obsessed with the in-story film also named Valis and how it seems to parallel events from their own lives. This ties into the novel's Gnostic themes (the film is a sign from a higher power that time is a cycle and the physical world is an illusion) but the Doylist reason is that Valis the film is based on Philip K. Dick's very early draft of VALIS the novel, from back when it was still under the working title Valisystem A. (Years later, Dick's Valisystem A draft would be posthumously published as a standalone story, under the new title Radio Free Albemuth.)
- Christine Ha: Roys Bedoys: The characters watch Chijimon, a web series that was also created by.
- Kazuma Kamachi: In later volumes of A Certain Magical Index, there may be one-shot scenes of someone watching something that is based on Kamachi's other works. In NT Volume 1, the B-movie that Shiage Hamazura and Saiai Kinuhata end up watching is Heavy Object. In NT Volume 11, a scene from The Zashiki Warashi of Intellectual Village is playing on a TV screen in a restaurant where Misaki Shokuhou is eating lunch.
- David Mitchell (Author): Cloud Atlas has a nested story structure, and at least some of them are fictional in-universe; the fourth story, "The Ghastly Ordeal of Timothy Cavendish", mentions that Cavendish, a publishing agent, read the third story, "Half-Lives", as a fictional narrative. "Half-Lives" includes Sixsmith from the previous story, "Letters from Zedelghem", in which the primary character reads the first story in the novel, "The Pacific Journal of Adam Ewing". "The Ghastly Ordeal" is then adapted into a film, which is watched by Sonmi-451 in the fifth story, and Sonmi's Orison is then watched by Zachry in "Sloosha's Crossin' an' Everythin' After".
- Kim Newman first introduced The Secrets of Drearcliff Grange School as a fictional novel within An English Ghost Story (which includes a section supposedly taken from the novel), but then wrote it in real life.
- Chuck Palahniuk occasionally references his book Fight Club in his other works. Usually with another character making fun of the film's Adaption Displacement by questioning, "What book?"
- Robert Rankin's sixth Brentford novel, Sex and Drugs and Sausage Rolls, is about the characters creating a stage show based on Rankin's novel Armageddon: The Musical.
- Rainbow Rowell: Carry On is, per Word of God, a fanfic of the Simon Snow series, which exists in the universe of Fangirl. Both books are written by Rainbow Rowell.
- In Raymond Smullyan's The Chess Mysteries of Sherlock Holmes, its companion volume The Chess Mysteries of the Arabian Knights exists as a manuscript by "Nayllums Dnomyar". Holmes finds the manuscript in Captain Marston's library, and it proves to be the key to decoding the location of Marston's treasure.
- Catherynne M. Valente initially mentioned The Girl Who Circumnavigated Fairyland in a Ship of Her Own Making as a fictional children's book within her novel Palimpsest, but then wrote it and several sequels in real life.
- Web Serial Novels by Wildbow:
- In the Parahumans series, a young adult book and film series, Maggie Holt seems to be based on the exploits of the character of the same name from Pact (who is a secondary character there, not the protagonist).
- Conversely, in Pact, the tabletop game Weaverdice, which is based on the Parahumans universe, is mentioned.
- William Dozier: Batman (1966): One episode features Bruce and Dick watching The Green Hornet - also produced by showrunner William Dozier - on TV. This in no way precludes Batman and Robin actually teaming up with the Hornet and Kato later in the season.
- Neil Gaiman: Good Omens (2019): In "The Doomsday Option", a soldier outside the base is reading American Gods, another Neil Gaiman-penned work.
- Lee Goldberg: In the Monk episode "Mr. Monk and the Captain's Marriage", one character has been reading Diagnosis: Murder book "The Waking Nightmare" by Lee Goldberg.
- Dan Harmon: Community: in Season 5 Episode 6, Abed and Rachel are seen watching Dan Harmon's other big series Rick and Morty during the ending montage.
- Stephen King: In Kingdom Hospital several characters are seen reading King novels, including Misery and Bag of Bones.
- Chilla's Art: Parasocial: The game starts off with Niina doing a livestream where she plays a top-down version of Aka Manto, one of Chilla's earlier games, but she soon quits after finding it too difficult. This ends up kicking off the plot, as she asks the chat for a new game to play. In the true ending, Asuka suggests she stream The Convenience Store, another Chilla game.
- Danganronpa V3: Killing Harmony: The Reveal has it where the previous entries in the franchise are treated as such when Tsumugi revealed that after the success of the original Danganronpa, Team Danganronpa decided to turn the franchise into a reality show by brainwashing people into thinking that they are actually Danganronpa characters. The fact that Tsumugi can cosplay as the characters from the first and second games is what gets the group to realize those characters are fictional as Tsumugi can't cosplay as real people.
- Game Freak: In the original Pokémon Red and Blue not only there is a Console Cameo of the Super Nintendo Entertainment System, but the game in the console is Mario & Wario.
- NomnomNami:
- her tears were my light is an odd case. In the Lonely Wolf Treat games, there are two characters named Thyme and Spice who claim to be fans of the aforementioned story and like to cosplay as its main characters Time and Space. However, the webcomic another piece of candy would later reveal that Thyme and Spice are mortal incarnations of Time and Space. So basically, Time and Space were reborn in an alternate universe where their own universe is a work of fiction.
- KAIMA appears as a film series in Mermaid Splash! Passion Festival and as an anime in another piece of candy.
- Syrup and the Ultimate Sweet apparently exists as a video game in the world of Mermaid Splash!, judging by the fact that CiCi is an avid Syrup x Butterscotch shipper.
- Kotaro Uchikoshi: In AI: The Somnium Files characters mention that Nine Hours, Nine Persons, Nine Doors is stated to have a movie adaptation in development.
- Rundisc: Chants of Sennaar shows a battle in Varion (their previous game) on a screen on the top level.
- Sounding Stone: The Peacemaker Series of fantasy RPG games exists in the Physical Exorcism Series, which takes place in the modern world, as an in-universe video game series that Sally and Lily are fans of, as revealed in Case 03: True Cannibal Boy. However, the true ending of Case 03 also reveals that Nya somehow has influence over both worlds, as they send Jade there from her world to act on their behalf.
- Rick Griffin: In A&H Club the main characters go to a movie based on Griffin's novel Traitors, Thieves, and Liars in one arc.
- Andrew Hussie: Homestuck: The webcomic Sweet Bro and Hella Jeff, which predates Homestuck, was later integrated into it as a Show Within a Show. Within Homestuck canon, it is created by the character Dave Strider. In real life, both comics are created by Andrew Hussie.
- Mastergodai: In the world of Rascals the artist's other comic Knuckle Up is a cheesy sci-fi show in which the Gender Bent protagonist is played by a pair of Half-Identical Twins.
- Alice Oseman: Several characters in Heartstopper are seen in the background reading other books by Heartstopper author Alice Oseman.
- Jan Tigerknight: In Nine to Nine Tor and Andrea (aka "Silver") make Swords and Sausages as a series of web videos. Explaining how the characters can be in both comics but have drastically different personalities (especially Andrea/Silver). Though Andrea once stumbled upon a portal to the "S&S" verse.
- Marvel: In Hit-Monkey, Akiko is shown reading The Punisher in her home.
- Matt Groening: The Simpsons: In "My Big Fat Geek Wedding", the characters meet Matt Groening at a sci-fi convention and recognize him as the creator of Futurama. Years later, The Simpsons would get a crossover episode with Futurama.
- Nickelodeon:
- The Loud House: In one episode, a TV seems to be playing SpongeBob SquarePants in the background.
- Rugrats: Their The Twelve Spoofs of Christmas song has Nickelodeon being the thing the babies watched on the Second Day of Christmas.
- Trey Parker and Matt Stone: The South Park episode "A Very Crappy Christmas" features the four boys creating The Spirit of Christmas.