Spooky, A.K.A. Experiment 300, is an illegal genetic experiment created by Jumba Jookiba. He is designed to terrorize his victims by morphing into their worst fears; his transformations are distinguishable by his glowing green eyes and hissing voice. His one true place is greeting and scaring trick-or-treaters on Halloween, and (for the rest of the year) haunting the old, abandoned mansion. He is voiced by Frank Welker.
He was activated during Halloween when his pod rolled into a barrel of water. He turned into a wild cat to scare a mouse, dogcatcher to scare a dog, headless Lilo to scare Mertle and her friends, spider to scare Moses, water to scare Stitch, Cobra to scare Nani, clown to scare Lilo, mother to scare Pleakley, ex-wife to scare Jumba, etc. He reappeared in "The Asteroid" and morphed into an asteroid when Stitch warned him of the danger. He later scared Kixx and Pleakley by morphing into nightmarish versions of his true form. He was part of the "rebellion" in "Checkers".
Spooky causes chaos by fulfilling the purpose he was programmed for: terrifying his enemies by turning into their worst fears. However, he went further by directly harming his victims, aside from just scaring them, and seems to be more dangerous than most experiments. Originally malicious and slightly sadistic, he often chooses to not only provoke fear in his victims, but also cause other mental trauma such as sadness and terror. He tends to slither and hiss like a snake, despite his most common form of being a blob. When people are brave enough to stand up against his scares, Spooky becomes annoyed and apparently powerless against them. However, after being reformed, Spooky only scares people for fun on Halloween. He is also loyal and helpful to his friends, joining Stitch's rebellion to fight off Gantu.
In the form of an individual or other creature, Spooky is completely indistinguishable from the real thing, except for glowing, olive-green eyes and a hissing voice.
In his true form, Spooky is a green blob-like experiment with glowing, olive-green eyes, a wide mouth with a turquoise tongue, a hissing voice and three round, short stubby spikes on his back, greatly resembling the other Disney (and Halloween-based) character Oogie Boogie.
Spooky can shapeshift/morph into his victims' deepest, darkest fears by taking the form of any person, animal or object. How he knows what his victims' fears are without finding out anything about them, though, is unknown. Spooky also turns elastic when moving. He uses a form of telepathy to read his victims' minds and discover their fears.
Spooky has morphed into many forms. These include:
- A wild cat
- A dogcatcher
- A fat, elastic, slug-shaped version of his true form
- Headless Lilo (Mertle and the hula girls' worst fear)
- A giant spider (Moses' worst fear)
- Floodwaters (Stitch's worst fear)
- Cobra Bubbles (Nani's worst fear of him taking Lilo away)
- A clown (Lilo's worst fear)
- Mrs. Pleakley (twice; Pleakley's worst fear)
- Jumba's ex-wife (twice; Jumba's worst fear)
- A water monster
- A twister
- A People Eating Pest Monkey (from The Origin of Stitch)
- A bat
- A giant python
- An asteroid
- A spiky, sea urchin-like fruit
- A version of his true form with massive fangs
- A large, muscular version of his true form with an alligator-like snout (a.k.a. "Spookymorp" according to Stitch's Great Escape!)
- A Goo Gobbling Booger Beast (from The Origin of Stitch)
- A zombie
- Angel (when she's angry at Stitch)
- A Tigerlily dinosaur-like creature
Spooky made an appearance in the Stitch! anime when Hämsterviel sent him along with Toons to scare the children of a summer camp. It is shown that he uses a form of telepathy to read his victim's mind and discover their worst fears. In "Shogun", it is shown that Spooky was dehydrated back into an experiment pod and locked in Jumba's vault.
- Spooky was first revealed in a DVD bonus feature of Stitch! The Movie in the experiment gallery.
- Spooky bears a great resemblance to Oogie Boogie from The Nightmare Before Christmas.
- Spooky has glowing, olive-green eyes instead of black ones like most of the other experiments.
- Jumba also referred to Spooky as "X300" and mentioned that his impression of Jumba's ex-wife is frightening.
- Disney has used "X-" (X with a hyphen) in promotional material as a shorthand prefix for "Experiment".
- Unlike most experiments, Spooky's number is pronounced as a whole number ("three hundred") instead of three individual digits (which in his case would have been "three-oh-oh") as per the norm for the experiments.
- The only other canonically-seen experiment whose number is also referred to as a whole number is Woops (Experiment 600). This implies that experiments whose number is divisible by one hundred (100) are the primary exceptions to the normal by-digit pronunciation of experiment numbers.
- Spooky's pod color is green.
- Spooky is described by the experiment computer screen as, "Experiment 300. Primary function: Morphs into the victim's worst fear".
- Spooky makes a cameo in the pre-show of Stitch's Great Escape! when Gantu shows guests a quick look at the "criminals" of the galaxy (which are all experiments). However, he does not appear in his default form, but rather the large form with an alligator-like snout that he tried using on Pleakley in "The Asteroid". Underneath the image, his name is rendered as "300M/Spookymorp" (presumably meant to be "Spookymorph") in Tantalog.
- Spooky's powers and abilities resemble the Boggarts in the Harry Potter series, as they are able to turn into their victims' worst fears.