Snafu

 Snafu, A.K.A. Experiment 120, is an illegal genetic experiment created by Jumba Jookiba. He is designed to foil enemy plans. He is designed to foil enemy plans by any means necessary. His one true place is with the military. Snafu is voiced by Frank Welker.

Bio
Experiment 120 was the 120th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to foil all and any plans he discovered at all costs.

120 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 120's pod was found by Jumba and kept in a shoebox under his bed.

Lilo & Stitch: The Series
Lilo discovered 120's pod in a shoebox when she was searching Jumba's room for any unactivated experiments to use in a rescue mission to free Stitch's cousins.

Jumba warned Lilo not to activate 120 when making a complex rescue mission. However, at that moment, Pleakley sprayed water everywhere with a hose, activating 120. 120 then ripped up the blueprints for Lilo and Stitch's rescue mission, and escaped through the pet flap.

120 remained near the house, where he spied on Lilo, Stitch and the experiments' plans for the rescue mission and sabotaged their obstacle course.

120 later foiled Gantu's plan to revert all of the experiments to evil by swapping the tape of Angel's song with Gantu's karaoke tape.

When Lilo, Stitch and the experiments launched a rescue mission on Gantu's ship, 120 tricked Sample into imitating the ship's alarm to alert Gantu. 120 then rewired the ship's experiment prison, causing it to trap the rescue team.

However, 120, named Snafu, did not count on the prison trapping him as well. But after hearing Stitch confess his love for Angel, Snafu cried as it touched his heart, causing him to turn from bad to good.

Fortunately, Snafu was freed by Angel and Stitch (who also freed the other captive experiments). Snafu then foiled Gantu before the latter could recapture the freed experiments, and escaped the ship with Lilo, the rescue team, and the released experiments.

Leroy & Stitch
The first 624 experiments, including Snafu, were round 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.

It is unknown whether or not Snafu participated in the following battle between the experiments and the Leroy clones.

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 failsafe.

Trivia

 * Snafu is named for the acronym SNAFU (Situation Normal All Fouled Up)
 * Snafu's pod color is purple.
 * Snafu is described by the experiment computer screen that says "Experiment 120 Primary Function: Discombobulates enemy plans."
 * Despite being perfectly unharmed during the events of Leroy & Stitch, Snafu made no attempt or even showed any knowledge of Hämsterviel's plot.