Hammerspace Hideaway

Hammerspace is a convenient place for characters to carry around mallets, anvils, fridges, or whatever else they need to advance the plot in a very small space. But what do you use to store a whole person?

This trope occurs when whole characters manage to hide themselves away into incredibly small spaces. It could be inside a shoe, or a suitcase, a jewelry box, in a friend's pocket, or behind a telephone pole.

Where ever the hideaway is, it must be an area so small that even if the character were to scrunch up and get squeezed into the space, it would still be too small for them, making Hammerspace the only plausible explanation for how they could possibly fit.

When characters use Hammerspace to disappear behind narrow poles, they are Behind a Stick. If a character turns out to be living inside a Hammerspace Hideaway, then it is probably a Clown Car Base instead. If we can see inside the Hammerspace Hideaway, then it will likely be Bigger on the Inside. Compare Party in My Pocket. See Behind the Black for similar situations resulting from the Rule of Perception.

Examples of Hammerspace Hideaway include:

Anime and Manga

In Mahou Sensei Negima, Kaede's Artefact is a cloak (essentially a flat piece of tattered cloth) that can hide several people inside... it does have a fully furnished house in there after all.
In One Piece, Capone Bege has the ability to miniaturize things to fit within his body (the inside of which appears to be like a castle).
Played with in K-On! The Movie, when Yui briefly considers how to pack her sister Ui in her already-overstuffed suitcase the night before she goes on a trip to London, England.

Comic Books

Scott Pilgrim can fit inside Ramona's shoulder purse.

Literature

There is that addition to the good ship Gay Deceiver in the Robert Heinlein novel The Number of the Beast.
The real "Mad-Eye" Moody turns out to be stuffed in his own trunk in Harry Potter and the Goblet of Fire. Said trunk is Bigger on the Inside thanks to its enchantments.
Chiron's Super Wheelchair in Percy Jackson and The Olympians, where he hides his horse legs.
Not the most extreme example, but in the first book of The Mysterious Benedict Society trilogy, Reynie, Kate, Sticky, and Constance are forced to squeeze into a very small crate to hide from Mr. Curtain. The illustration does not at all look comfy.

Live-Action TV

Wizards of Waverly Place: Alex invoked this to sneak Harper onto the S.S. Tipton by hiding her away in her suitcase. Justified in that the suitcase is magic.
There was once an episode of Scrubs where Turk sneaked JD around in his backpack.
One common gag in Shake It Up involves cute kid Flynn stowing away in his sister CeCe's suitcase, even when it's filled to capacity.
- In the Good Luck Charlie crossover episode, Flynn, along with Rocky, CeCe, and Deuce, all stowed away in Teddy's luggage. Rocky and CeCe hid in her suitcase, Flynn hid in her carry-on, and Deuce hid in her purse. Yeah, her purse.
Danger 5 reveals Stalin's moustache is one of these. Seen here.

Tabletop Games

Several types of Exalted have access to Charms that allow them to store objects Elsewhere. Lunars, however, can actually learn Charms that allow them to create tiny little dens in Elsewhere, safe places they can escape to on a moment's notice.
Dungeons & Dragons:
- The arcane spell Rope Trick allows the caster and several friends to climb up a rope and "vanish" into a small extradimensional space at the top that holds several people and potentially even lets them to pull up the rope after them as well, making for a quite safe retreat, for the duration of the spell, of course. There's also Leomund's Tiny Hut, which creates a dwelling the size of a tent that an adventuring party can sleep in (providing heat and protection from the elements) and the most powerful version, Mordenkainen's Magnificent Mansion, which is an entire house created in an extradimensional space, usually used by wizards to conduct experiments in private. It includes Unseen Servants to help him, and also creates food. The downside is, the food isn't real, and anyone who lives on it while inside becomes incredibly hungry upon leaving, and has to eat immediately afterwards. At least one module centered upon a wizard who was well-known for being a Big Eater because he secretly used this spell very frequently.
- A famous example is the notorious artifact Baba Yaga's Hut. It appears as a small, thatched hut with large legs resembling those of a giant chicken, and is usually dancing when found (indeed, whether it can be better described as a "magical item" or a "magical creature" is debatable). If a wizard of considerable skill convinces it to obey and enters it, it proves far bigger on the inside, being a rather large palace, with lavishly furnished bedchambers, banquet halls, an alchemy lab, a complete library, and even an observatory. One peculiar thing about the place is that while many of the interior rooms have windows, all of them offer the same view, that from the two windows on the front of the Hut that can be seen from outside. One source suggests that the Hut has a hidden brain within it somewhere, and destroying it is the only way to destroy the Hut; likely, this is something that only Baba Yaga herself, it's true owner, knows the location of. All sources hint that the Hut likely has secrets known only to her, and the Game Master is not recommended to introduce the Hut into a campaign unless he is also willing to introduce her as a villain. The Hut is her home, and sooner or later, she will come to get it back.

Video Games

In The Legend of Zelda: Majora's Mask, the Deku princess somehow gets put into one of Link's bottles, despite being normally almost as tall as Link himself.
One of Dr. E. Gadd's new inventions in Luigi's Mansion 3: His portable lab! It starts out as a breadbox-sized, dome-shaped object, and with the touch of a button, expands into a cottage-sized lab, complete with his ghost-containment device and computers.

Western Animation

SpongeBob SquarePants: One episode had Patrick's head come out of a hat box, which was itself in a television box.
Animaniacs: Dot had a special box in which she keeps a gigantic monster. The Warner brothers themselves can pop out of incredibly small places as well.
Ed, Edd 'n' Eddy: The Eds often end up in some very small places.
- Eddy once managed to stuff himself into a bucket.
- Edd managed to fit inside his sock hat.
Looney Tunes: Bugs Bunny is known for stuffing some of his foes into rather tight spaces. For example, in "Bugs and Thugs", Bugs stuffed two fully grown gangsters into a rather small oven...twice!
- Another gag is the folding box. put someone in it, fold it like cardboard, then fold it again... and again...
The Fairly OddParents: "I will now hide inside my own pants. Presto!" Timmy succeeds... until Vicky yanks him out.
Family Guy: "Peter, get out of the fridge!"
The closet doors from Monsters, Inc..
Danny Phantom uses this plenty. One wonders how a soup can can hold an unlimited amount of ghosts. It's even lampshaded at one point:

Danny: How on earth did they cram all of you into the Spectre Speeder?
Ember: You ever been stuck inside your stupid Thermos? Compared to that, it was the Taj Mahal in there!

Real Life

One variation on a very old joke about a scientist, a mathematician, and an engineer ends with the mathematician inside a can of beans.
Several people smuggled girlfriends/wives out of East Berlin in some impossibly tight spaces like a suitcase (or two) and a car seat (the person was literally inside the hollowed-out car seat).
Most versions of the classic magic trick of Sawing a Woman In Half -- including its more spectacular modern descendant, the Zig-Zag Woman -- rely on the woman concerned being able to contort herself into small, disguised spaces within the table or other prop being used.