Nosy

Nosy, A.K.A. Experiment 199, is an illegal genetic experiment created by Jumba Jookiba. He is designed to snoop out and reveal his enemies' most embarrassing secrets, but tends to dig up mostly useless gossip. He was captured by Gantu, but escaped in "Woops". His one true place is as a journalist.

Personality
Nosy behaves exactly the way he was designed and programmed. He would uncaringly nose his way through other people's business. It doesn't matter who or what; he'll somehow try and find any juicy info that can be listened to or read. He'd want to look into your diaries, journals, photos, and even newspaper or magazine personals. All for his next phase of action....

After some shuffling around through your personal business, Nosy would still look around for anything else, but he will also tell anybody who talks to him (or even looks at him) whatever he's managed to dig up, mostly embarrassing things. This is useful if you need to know plans from friends or enemies, but otherwise useless because Nosy likes to yap on and on about much more humiliating secrets, rather than items of strategy. It's his glitch, you can't blame the guy.

One of Nosy's most biggest characteristics is his rather big mouth. Not just literally – he could talk for hours about stuff. All of these, however, are simply in his programming. He still does feel a great deal of emotion, especially when it comes to things that are pinned on himself (like Lilo and Stitch never rescuing him from his capture).

Last of all, Nosy is never a fighter. When battle comes his way, he will most certainly run away screaming, rather than stand up and fight for himself. His possible motto is: "Don't fight but run away, live to gossip another day."

Lilo & Stitch: The Series
Experiment 199 was the 199th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to snoop out and reveal his victims' most humiliating secrets. 199 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.

All of the experiment pods were released and scattered across the island of Kauai.

At an unknown point after this, Experiment 199 was activated.

199, disguised as a kid, watched the new Wasp Mummies movie, then revealed the secret ending aloud to Lilo and Stitch before sauntering off. Stitch, at that moment, saw through 199's disguise and captured him.

Lilo and Stitch then took 199, named Nosy, back to their house, where he began to unearth and reveal numerous secrets.

When Keoni and Mr. Jameson arrived at the house, invited to brunch, Nosy intervened and revealed the Pelekais' secrets to the Jamesons, including Lilo's crush on Keoni.

As a result, Stitch got rid of Nosy, slammed a container over him, and delivered him to Gantu as a present. Delighted, Gantu persuaded Nosy to disclose all of Lilo and Stitch's experiment files. Instead, he only talked about useless information and revealed secrets about Gantu to Experiment 625, prompting Gantu to send Nosy to Hämsterviel.

However, when Nosy arrived and revealed Gantu and Reuben's secret disrespect towards Hämsterviel, the latter sent him back to Gantu as revenge (though Nosy was first able to steal Hämsterviel's diary). Nosy read Gantu Hämsterviel's diary, but the former was shortly after kicked out of Gantu's ship for the trouble he caused.

Thus, Nosy returned to the Pelekais' home, where he gossiped about more topics and exposed Stitch as an alien genetic experiment after their tussle. However, he was shortly after recaptured by Gantu, which Lilo and Stitch allowed him to do, but at Gantu's ship, Nosy and Reuben exchanged rumors about Gantu.

In "Spike", Nosy was one of the experiments in Pleakley's E.A.R.W.A.X. group. He revealed to the entire group that Pleakley's antenna was prematurely orange and simply dyed green before Pleakley silenced him. Shortly after, Pleakley used Nosy in his aromatherapy (in which he rubbed Nosy with a smelly fish). When the other experiments instead began to cause chaos, Nosy was chased by Spike through the house. Near the end of the episode, Nosy tried out Pleakley's hugging-and-crying therapy.

In "Woops", Experiment 600 accidentally smashed open Nosy's containment orb, allowing him to escape.

In "Snafu", Nosy traveled to the Pelekais' house, angry with Lilo for abandoning him and the other captive experiments to Gantu. He also revealed when Gantu's ship was empty and spied on Gantu and Reuben.

Leroy & Stitch
The first 624 experiments, including Nosy, were rounded up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.

Nosy did not participate in the following battle between the experiments and the Leroy clones, instead choosing to retreat with the weaker experiments.

The Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song "Aloha `Oe," which caused the Leroy army to shut down due to the original Leroy's fail-safe.

Stitch! anime
Nosy has appeared multiple times in the Stitch! anime where he revealed everyone's secrets around the island and divulged Delia and Hämsterviel's plans to Jumba.

Trivia

 * Nosy bears a strong resemblance to Pain from Hercules in both appearance, personality, and even sharing the same voice actor, Bobcat Goldthwait. The main difference is that Nosy reforms and becomes an ally to the protagonist, while Pain remains evil and loyal to the antagonist.
 * His name could be derived from both his abnormally sized nose and the adjective meaning "showing too much curiosity about other people's affairs."
 * In "Spike", Nosy was at Pleakley's E.A.R.W.A.X. group, but Gantu captured him. Though he could have temporarily escaped somehow, which would qualify him as a truant experiment.
 * It is also possible that the episode chronologically takes place after "Snafu", given that Fibber is also present.
 * Nosy's pod color is purple.
 * Nosy is described by the experiment computer screen as, "Experiment 199. Primary function: Digs up dirt."
 * Aside from Sparky and Angel, Nosy has made the most multiple appearances in the Stitch! anime.