Topper

Topper, A.K.A. Experiment 025, is an illegal genetic experiment that was created by Jumba Jookiba. He is designed to give off a bright light with which to pose as an invasion-signaling beacon to the Galactic Armada. His one true place is as a Christmas star. Topper is voiced by Tress MacNeille.

Lilo & Stitch: The Series
Experiment 025 was the 25th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to use his bright light to pose as a beacon for an invasion to the Galactic Armada. 025 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.

025's pod was found by Gantu on Christmas Eve, which was intended to be sent as a Christmas present meant for Hämsterviel.

Meanwhile, Lilo was trying to teach Stitch about Christmas when the latter suddenly noticed a woman giftwrapping 025's pod. Stitch hastily swiped what he thought was the gift with the experiment pod, but when he tried to tell Lilo, she ignored him.

In an attempt to find the pod, Stitch stole countless presents from every house and the local shopping mall, while Lilo mistook Stitch's behavior for trying to selfishly hoard presents for himself.

After being captured and interrogated, Stitch revealed to Lilo and the others what he was really trying to do. Just then, Gantu attacked the house and made off with all the gifts that Stitch had stolen earlier.

When Lilo, Stitch, Jumba and Pleakley pinpointed the giftwrapped pod, the four tussled with Gantu dressed in a Santa suit. Gantu eventually reclaimed 025's pod, then attempted to crush Lilo for her meddling. However, Gantu had a change of heart after grasping the meaning of Christmas, as he gave the pod to a little girl and later distributed presents to other children.

After Jumba discovered 025 to be harmless, Lilo activated 025 in a fountain and shared him with the same little girl from before. She then named him Topper and gave him a one true place atop the local Christmas tree (actually a decorated Pleakley) as a Christmas star, while Topper's bright light unintentionally signaled the Galactic Armada.

Topper reappeared in "Elastico" as one of the audience for Lilo's hula dance.

The Origin of Stitch
Topper was one of the experiments that was gliding on the screen, but he is 591 instead of 025.

Leroy & Stitch
The first 624 experiments, including Topper, 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.

Topper 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 fail-safe.

Trivia

 * Topper's primary function is to use his bright light to signal the alien attack fleet. However, on the Disney site, it is incorrectly stated that Topper's light is designed to keep people awake.
 * Even though Topper was found a one true place on a Christmas tree, it is unknown what he does during the other seasons.
 * Topper's pod color is white.
 * Topper is described by the experiment computer screen as, "Experiment 025 Primary function: Keeper of awakeness to people."
 * His number is likely a reference to Christmas Day (December 25).