Little Stowaway

In fiction, children have a habit of hiding on ships, airplanes, spaceships, etc., whenever they decide to go on an adventure.

When they are discovered, the adults are frequently unable to leave them behind, for some reason or other.

Examples of Little Stowaway include:

Anime and Manga

Spridle and Chim Chim of Speed Racer.
In Haruhi Suzumiya, Kyon's little sister hides in his travel bag to go with him on a vacation. Of course, she is instantly discovered, but in the anime version, they ultimately allow her to go with them.
Thorfinn in Vinland Saga.
Ed from Cowboy Bebop.
Gruelle in Bodacious Space Pirates.

Film

In Stowaway to the Moon, a pre-teen boy stows away on an Apollo mission.
Russell in Up, though accidentally.
The Lost World: Jurassic Park
The Incredibles
The film version of The Voyage of the Dawn Treader has a little girl stow away on the ship to be with her father.

Literature

Arthur C. Clarke's Dolphin Island: A cargo hover ship makes an emergency landing in the United States and a teenager named Johnny Clinton stows away aboard it. A few hours later it crashes into the Pacific Ocean and Johnny is rescued by dolphins, who take him to safety on an inhabited island.
Arkady Darell in Second Foundation.
Peewee in Robert A. Heinlein's Have Space Suit—Will Travel
Marilyn in The Cold Equations. The pilot tosses her out of the airlock.
The boy in My Father's Dragon does this to get to the island of the animals.
Esk in Equal Rites.^[context?]

Live-Action TV

This is how Adric got on the TARDIS in Doctor Who. Many fans would not have objected to him being Thrown Out the Airlock, though.
- And Zoe. It seems to be a mathematician thing.
  - Also Toby stows away on his father's pirate ship in The Curse of the Black Spot.
Lupus is a stowaway on Marcus Flavius's ship on the TV adaption of The Secrets of Vesuvius.

Video Games

This is how Sothe originally joins your party in Fire Emblem: Path of Radiance. He's stowed away on your party's ship when they sail to Begnion.
A sidequest in Knights of the Old Republic involves a girl who had been kidnapped by the Mandalorians, escaped, and stowed away on the Ebon Hawk. Your options are to tell her to leave, learn to communicate with her (she speaks a garbled form of Mandalorian) and reunite her with her family, or wait until she leaves on her own.
In Sam and Max: The Tomb of Sammun-Mak, Sam and Max's great-grandfathers Sameth and Maximus discover that Baby Amelia Earhart has stowed away in their luggage on the Disorient Express.
A 17 year old Lara Croft does this in Tomb Raider: Chronicles.
In Skies of Arcadia, Marco stows away on the Delphinus because he's tired of living in Lower Valua. He winds up becoming the first official non-playable member of Vyse's crew.
Maribel attempts to stow away on her father's fishing boat at the start of Dragon Quest VII. The Hero has to blow her cover and get her kicked off the boat, setting the scene for her to join the real adventure later.
In Infinite Space, Katida Lanco sneaks onboard the player's ship after being rescued. Unfortunately, she suffers from a medical condition that makes long-term space travel almost impossible.

Web Comics

In Nip and Tuck, the Show Within a Show Rebel Cry features a kid stowaway.
In Impure Blood, how Mac gets on the airship.

Web Original

In Project Million, Mikey Insanity stows away in LC's suitcase in order to get to Florida.

Western Animation

Jade of Jackie Chan Adventures does this.
As does Penny in Inspector Gadget, though she always hides herself from her Uncle (and often gets caught by the villains instead).
Lampshaded in the Jonny Quest TOS episode "Terror Island". When Race Bannon arrives at the island by boat, he says that the boys (Jonny and Hadji) can come out now. When they ask how he knew they were there, Race says that they've pulled the "stowaway bit" so often that he's come to expect it.
In one episode of The Simpsons, Bart hides in a fishing boat that gets in a storm and Homer discovers him just before the Giant Wall of Watery Doom gets in the ship.
Iceman (who is around 14 in this continuity), in an episode of X-Men: Evolution, stows away in the X-Jet so he can fight with the X-Men vets. It works partially - he managed to hitch his ride, but Professor X knew he was there all along.
- It was also an excuse to have a team made up of the Original Five X-Men from the comic books for an episode. Mythology Gag for the win!
- Another episode Grim Reminder, have Shadowcat and Nightcrawler, worried about Wolverine, stow away on the X-Jet when he goes back to the site of Weapon X.
  - That's not as much stowing away as being taken accidentally - Kitty was looking for a quiet place to write her parents an e-mail, and Kurt just showed up to mess about with her.
Adult version (well... Adult Child version) on Archer; Pam and Cheryl stow away on a space flight, largely as an excuse to put the comic relief characters in the episode even though it's implausible enough that the main cast are there...