An alternate or parallel universe inhabited by cartoon characters (usually zany, Looney Tunes-style characters) and governed by Toon physics and the Rule of Funny. It exists alongside a more realistic universe, usually portrayed in live-action.
Though the trope is sometimes played straight, it's also a frequent target of deconstruction. The latter may highlight the impossibility of Toon physics, the violence in nominally kid-friendly cartoons, or the fantastic racism that might ensue if Toons really existed. Or any number of other things, really.
- Captain Carrot and His Amazing Zoo Crew! originally took place on an alternate Earth (Earth-C), which Superman crossed over into once. They have their own alternate too, Earth C-Minus, where the events that Rodney Rabbit writes in comic books take place for real. After Final Crisis, the Zoo Crew's world became Earth-26 of the DC multiverse.
- Ghostbusters (IDW) initially had two Ghostbusters universes: one in which Ghostbusters (1984), Ghostbusters II, the 2009 video game, and the IDW series take place, and one in which the animated series The Real Ghostbusters and Extreme Ghostbusters take place, and the films are fictional. While there are some callbacks and references between the two (mostly in the form of background gags, although Janine's appearance in the comics is a hybrid between her cartoon and film appearances, and an alternate version of Kylie from Extreme Ghostbusters is part of the New Ghostbusters team), they remained mostly separate... until 2015, when IDW did a limited-miniseries crossover between both 'verses. The Ghostbusters (2016) universe was added in 2017 with another miniseries crossover, and it became a full-on multiverse in a 2018 miniseries crossover, which among other things introduced the universe of the Tokyopop Ghostbusters manga, and a universe that ran ahead of the Real Ghostbusters universe, where it's currently the Extreme Ghostbusters era.
- Howard the Duck comes from an anthropomorphic-animal universe, albeit without actual cartoon physics.
- In the Animal Man comic The Coyote Gospel, a Wile E. Coyote expy is banished to "the hell above" — reality — for daring to question why cartoon characters must live such painful, violent lives. He appears on Earth as a grotesque "realistic" incarnation of himself, and becomes a messianic figure by taking on all other Toons' pain as his own — by being killed in various ways and springing back to life, forever, on the same lonely desert road.
- This is the explanation in some (but by no means all) DC Comics Meet Hanna Barbera and DC Comics Meet Looney Tunes oneshots.
- Tom Strong had Funnyland, home to Righteous Rabbit Warren Strong, his wife Patience, their daughters Topsy, Turvey and Fluffytail, and their Cunning Like a Fox enemy Basil Saveen. Funnyland reappears, along with some other alternate universes from Tom Strong, in The Terrifics, where it's also home to the Dr Dread counterpart Ducktor Dread.
- The Doctor Who "outside continuity" pub This Time Round has an alternate tooniverse called This Toon Round, which contains toonified versions of Doctor Who characters (including Tardis Tails the cat and Lizzy the lizard from one very weird Doctor Who Magazine story) and TTR's own cast (including Author Avatars) as well as various British cartoon characters such as Danger Mouse and Wallace & Gromit.
- Boonie Bears: Entangled Worlds, based off the hit Chinese animated show, suggests that the Boonie Bears universe is this trope, as the main antagonist is an intelligent businessman who lives in the live-action Science Fiction-fueled universe, and sends a Terrible Trio of humans to raid powerful objects from animated universes. Interestingly, unlike most examples here, the humans from the live-action universe are animated in the "tooniverse".
- Garfield Gets Real, where both the "real world" and Garfield's world are CG animated.
- While Spider-Man: Into the Spider-Verse is CGI, some dimensions are given heavy stylisation, making them read as "tooniverses" in comparison to the more "realistic" worlds of Miles Morales, Peter B. Parker, and Gwen Stacy; Peni Parker is an anime character complete with Mouth Flaps that don't sync up with her actual speech, Spider-Ham is a Tex Avery cartoon character who can produce hammers and anvils from nowhere, and in The Stinger, Miguel O'Hara finds himself visiting the 1960s Spider-Man cartoon. Scorpion even refers to Spider-Ham as a "cartoon" during the final battle.
- Cool World: an alternate universe exists, populated by toons (or Doodles as they were called; the humans were called Noids).
- Enchanted, which examines how common Disney Princess tropes would work in the real world. Oddly enough, it wasn't supposed to be a Disney film at first, but became one.
- In Space Jam, the Looney Tunes characters live in an alternate world that can be reached from an underground portal in the center of the Earth.
- In Twilight Zone: The Movie, during "The Good Life" segment, Anthony uses his powers to send his "sister" Ethel into the cartoon world, where she's chased around for a moment before being eaten. In this case, though, Toontown exists because of Anthony's dark powers.
- Mary Poppins and company jump into a chalk painting and end up in a world like this.
- Who Framed Roger Rabbit mostly has toons in the real world, except when Eddie chases Roger to Toon Town. There, cartoon physics take over and any human is subject to them: Eddie sneezes and his cartoon shadow turns with, "Gesundheit"; his toon bullets change direction mid-flight; Tweety pries his fingers off a flagpole and he falls a gazillion stories before being caught by Lena Hyena...
- Invoked in Community, when Abed manages to convince Troy that he's found a doorway to a cartoon world outside Greendale Community College by painting an animated version of himself on a wall:
Troy: That's impossible!
Abed: Nothing's impossible in here! Animals can talk, your heart is shaped like a heart, and the smell of pie can make you float! You have to believe, Troy!
[Troy is just about to run headlong into the wall when:]
Abed: [leaping out from behind a bin] Wait! You don't have to believe.
Troy: [clearly heartbroken] I didn't!... I didn't... [he storms off]
Abed: I may have done some damage there.
- The Fringe episode "Brown Betty" might have featured such an alternate universe, as seen when story-world Nina Sharp communicates with story-world William Bell using the window device (though this may have been a choice to go for a retro-aesthetic).
- The series regulars of the CW's Supernatural get sucked into a cursed TV and into the Scooby-Doo episode 'A Night of Fright Is No Delight." They try to go through the motions with the Scooby gang as per the episode's normal continuity but that gets deep sixed as characters are killed off and painful real-life injuries are sustained. Once Sam, Dean and Castiel figure out what's really going on, they now have to establish the status quo of the standard "Scooby-Doo" Hoax.
- Toon Struck: The protagonist, a cartoon animator, ends up in his toon world.
- The webcomic Hexenringe involves at least two dimensions - one like ours and one which is populated by comics characters and other fictional creations.
- Zebra Girl has an alternate universe with cartoon characters whose lives and personalities run parallel with those of the people of the main universe.
- The central plot of Kidd Video: a band of rock musicians is taken into a Toon Universe made of what seem to be MTV's commercial breaks and abstract animated music videos.
- The Aniverse in Bucky O'Hare has anthropomorphs aplenty, but sci-fi physics rather than cartoon ones.
- Timmy of The Fairly OddParents sometimes goes into the comic book world of the Crimson Chin.
- In The Real Ghostbusters episode Who're You Calling Two-Dimensional? the Ghostbusters get trapped in a cartoon world created by the mind of fictional animator Walt Fleishman.
- Similarly, an episode of The 13 Ghosts of Scooby-Doo had Scooby and the gang get transported into the comic book world of Platypus Duck.