Amnesio

Amnesio, A.K.A. Experiment 303, is an illegal genetic experiment created by Jumba Jookiba. He is designed to wipe the memories of anyone he zaps in the eyes with the rays from his own. He was captured by Gantu, but was rescued in "Snafu." Amnesio is voiced by Tress MacNeille.

Bio
Experiment 303 was the 303rd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to wipe his victims' memories.

303 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.

Lilo & Stitch: The Series
303's pod was used as a ping-pong ball until whacked off the table and into a little boy's bucket of sand. Thinking it was a marble, the boy put it on top of his sand castle. Then a small wave splashed on the castle and activated 303, named Amnesio.

Amnesio went on to start wiping everyone's memories until he was found by Gantu. However, Gantu was unable to catch Amnesio because he was in the air and was able to successfully evade all of Gantu's plasma blasts.

Gantu and Amnesio's presence captured the attention of Lilo and Stitch. Grabbing a butterfly net, Stitch climbed a telephone pole to try to catch Amnesio. Unfortunately, Amnesio sat on the telephone wire, and Gantu captured him in a containment pod. Before long, Lilo, Stitch and Gantu were fighting over the pod containing Amnesio, which ended with Amnesio wiping all three of their memories.

Plagued with amnesia, Lilo, Stitch and Gantu decided to team up and figure out what to do with the captured experiment. When Lilo discovered how to reverse Amnesio's effects, Gantu set Amnesio free.

Amnesio went on a second rampage and wiped Jumba and Pleakley's memories.

His effects were later undone from Lilo yelling "Ohana!", but Gantu got away with Amnesio in the end. Amnesio was successfully sent to Hämsterviel, but he ended up wiping Hämsterviel's memory as well.

Amnesio reappeared in "Snafu," and was freed along with Gantu's other captive experiments by Lilo, Stitch, and several other experiments in a rescue mission.

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

Amnesio participated in the following battle between the experiments and the Leroy clones by erasing Leroys' memories.

However, 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

 * The password which reverses Amnesio's memory-deleting powers is "ohana," a word which Amnesio's creator, Jumba, did not know of until well after Amnesio's creation.