Phantasmo, A.K.A. Experiment 375, is an illegal genetic experiment created by Jumba Jookiba. He is designed to possess inanimate objects and use them to create chaos. Being a ghostly experiment, he has intangible qualities and can phase through obstacles, thus making him virtually uncatchable. His one true place is inside the Macki Macaw animatronic at the pizza restaurant.
Phantasmo used to find delight in mischief, but he later decided that receiving constant attention was better than causing chaos. He would act inanimate because if anyone exposed him or knew his secret, he would then become feared or hated, so he would dispose of those who found out.
Experiment 375 was the 375th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to possess inanimate objects and, through them, cause massive mischief and chaos. 375 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.
375's pod eventually made its way into an oyster prize inside the Macki Macaw restaurant's crane game.
Stitch played the claw game and won the oyster, but a glitch in the device caused him to shake it in frustration. After the oyster freed itself, Lilo and Stitch took it home with them. There, an incident with the bathtub (due to Stitch resisting when Lilo tried to give him a bath) resulted in the oyster opening and the pod inside getting wet, activating 375.
That night, 375 wreaked havoc in the kitchen. When Stitch was alerted, he attempted to save Pleakley's dishes, but 375 made Stitch lose his balance and shatter them. 375 then possessed Scrump and used the doll to paint Nani's face green, sabotage Jumba's experiment analyzer, steal Pleakley's begonia, break Lilo's record player, brush Nani's toothbrush on Stitch's toes, and frame Stitch for it all.
The next morning, Nani, believing Stitch was the culprit, threw him outside and kept him chained up as punishment. However, Stitch then noticed 375, who repossessed Scrump and began unraveling Lilo's videotapes. Stitch broke free and attacked Lilo's doll, arousing her suspicion. When Stitch was being prosecuted, 375 winked while still inside Scrump, causing Stitch to lash out at Lilo's doll.
Later that day, while 375 was attempting to break Pleakley's flower pot to get Stitch in deeper trouble, Lilo caught him in the act. 375 suddenly revealed himself from Scrump and, while possessing a rope, tied Lilo, Jumba and Pleakley up. He then repossessed Scrump and prepared to execute the three with Jumba's blaster, but Stitch ambushed 375 and freed his ʻohana.
While the four searched for 375, he possessed a vacuum cleaner and almost sucked Pleakley up with it. Lilo and Stitch then made a vain attempt to catch the intangible 375, forcing the latter to retreat into Kokaua Town.
After a long pursuit through town, 375 followed Nani, Lilo, Stitch, Jumba and Pleakley to the Macki Macaw restaurant, where he used the claw machine to trap Stitch. The former then chased Lilo backstage and possessed the Macki Macaw animatronic that had malfunctioned sometime earlier. Before long, 375 put on a show for an audience after Lilo raised the curtain.
375, christened Phantasmo, was then convinced by Lilo that using the animatronic parrot to entertain children and gain appreciation was a better way of gaining attention than causing chaos.
Phantasmo made a cameo inside the Macki Macaw animatronic on TV at the end of "Snooty".
The first 624 experiments, including Phantasmo, 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.
Phantasmo 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.
- Phantasmo is clearly a spectral being, as he possesses intangibility and the ability to phase through obstacles, thus making him the only experiment that cannot be restrained or captured.
- Phantasmo's pod color is yellow.
- Phantasmo is described by the experiment computer screen as, "Experiment 375. Primary function: Spiritual possession."
- Phantasmo's ears appear in the online game Jumba's Lab.