Spike (Lilo & Stitch)

 Spike, A.K.A. Experiment 319, is an illegal genetic experiment created by Jumba Jookiba. He is designed to fire spines that make his victims goofy and stupid by decreasing the victim's intelligence by 99% when hit, leaving them only 1% clever for the next 48 hours. If the person has a very high IQ, the quills won't have any effect. His one true place is as a hugging therapist in Pleakley's E.A.R.W.A.X. group.

Personality
Spike is shown to be very troublesome, as his spines pose a dangerous threat to anyone pricked by them. However, he is not afraid to display emotion as seen when he shed noisy tears while Pleakley hugged him during the therapy program. This not only rehabilitated Spike, but also motivated him to follow Pleakley's E.A.R.W.A.X. method.

Lilo & Stitch: The Series
Experiment 319 was the 319th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to fire spines like darts that make his victims incredibly silly by causing any hit victim's goofiness to increase by 99%, leaving them only 1% clever. 319 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, with 319's pod landing by an outdoor stage.

When a clumsy servant dropped a water bottle onto the stage, the water trickling out touched 319's pod, activating the experiment. 319 then spiked the public speaker and servant, causing them to act goofy, and then attacked the entire audience.

Later, 319 attacked a museum and was captured in a containment orb by Stitch, but not before spiking him and Jumba. Fortunately, 319's goofiness-inducing spines didn't seem to affect Jumba as much as Stitch (since the former was already a genius).

319 was then taken back to the Pelekai household and named Spike, who was later kept in custody as one of the experiments in Pleakley's E.A.R.W.A.X. group.

While the captive Spike was being rehabilitated, Lilo made a vain attempt to get a goofy Stitch to become smart again in time for the upcoming Ohana-Rama contest.

During Pleakley's seminar, when a fight broke out between Slushy and Splodyhead, a stray fireball from Splodyhead destroyed Spike's container, freeing him. Spike then went on a rampage, chasing Nosy around the house and targeting Pleakley when the latter demanded the boisterous group to adhere to the therapy program.

Forced to resolve the issue, Pleakley left for a minute and donned protective knight's armor against Spike's spines. He then attempted hugging therapy on Spike, which surprisingly pacified the latter, who sobbed pitifully. Awed by Spike's turnaround, the other experiments tried out Pleakley's hugging-and-crying method.

The following night, Pleakley took Spike with him, Lilo, Stitch and Jumba to the Ohana-Rama. Spike then offered Lilo a hug to cheer her up when she felt down. Lilo declined, however, because although Spike was rehabilitated, a stray spine would likely affect her chances of competing.

Later during the contest, Lilo and Spike followed Stitch backstage to discover that Teresa was secretly helping Mertle cheat, so Lilo convinced Spike to hug Teresa, pricking her. She then began giving Mertle completely silly answers, thus ruining her chances of cheating. After Lilo won the Ohana-Rama, Mertle stormed out in a rage. Spike felt sorry for Mertle and decided to hug her as well, spiking the latter.

Spike was later found a one true place hugging and thus taming truant experiments in Pleakley's E.A.R.W.A.X. group, while wearing similar protective armor to cover his goofiness-inducing spines.

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

Spike participated in the following battle between the experiments and the Leroy clones by firing goofiness-inducing spines at Leroys.

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 fail-safe.

Stitch! anime
Spike has appeared multiple times in the Stitch! anime including one instance with Hammerface, Babyfier, Link, and Woody. He was also used by Hämsterviel to try to sabotage a quiz competition. His abilities were modified in this episode so that he only reduces the victim's intelligence, and it can be magnified by squeezing his nose. It is shown that he has the ability to roll into a ball and launch his spikes while spinning at incredibly high speeds.

Trivia

 * When Jumba got pricked by one of Spike's spines, he didn't act goofy since he was already a genius, possibly indicating that people with very high IQs are not affected as much.
 * Spike is clearly a porcupine-like experiment, but unlike him, real-life porcupines cannot throw/shoot their quills, nor are their spines poisonous.
 * Spike is one of the six known experiments to be rehabilitated by someone other than Lilo and Stitch, the other five being Gigi, Elastico, Yaarp, Frenchfry, and Snooty.
 * Spike's pod color is yellow.
 * Spike is described by the experiment computer screen as, "Experiment 319. Primary fuction: Makes victims act goofy and stupid."
 * In the anime episode "Link-age," Reuben states that Spike's favorite type of sandwich is shish kebab euro.