Experiment 628 is an illegal genetic experiment created by Jumba Jookiba. He turns humans into experiments. He was killed by Hamsterviel to destroy any chance of Hamsterviel being changed back from an experiment.
Shortly after creating 627, Jumba and Skipper created Experiment 628 from the blood of previous experiments, and injected him with DNA from Angel, Reuben and Stitch. Due to 628's invincibility, and the failure with 627, 628 was never activated, and his pod was locked away in a vault.
Five years later, while Pleakley was cleaning out the ship, he found 628's pod and threw it out, mistaking it for a golf ball. Hamsterviel later found the experiment pod in the garbage, and stole it and took it back to his bunker.
There, Hamsterviel activated 628 and released him into the island.
While Lilo and Skipper were searching the island for Hämsterviel's base, they came across 628, who attacked and stung both of them. However, before he could finish Lilo and Skipper off, Stitch and Angel arrived, forcing 628 to flee.
Some days - weeks later, 628 attacked the Pelekai household. He stung Victoria, and kidnapped Skipper and took him back to Hamsterviel's base.
16 and a half years after kidnapping Skipper, when HAmsterviel used a formula to turn himself into an experiment, he had 628 destroyed to get rid of any possibility of HAmsterviel being changed back.
When Reuben's ghost visited the ohana, he gave them a message from 628's ghost, apologizing for any trouble he caused them in life.
628 is virtually identical to Reuben, except he is dark-green with a squashed-in face, a tiny nose, and a six-foot, needle-like tail.
628's neurotoxin causes any stung human to transform into an experiment.
When a human victim is stung with 628's needle-like tail, they will pass out, and 628 will transfer a mixture of genetic information from Angel, Reuben and Stitch into the victim. After a matter of hours, the victim will recover from the attack, and the puncture wound from 628's tail will have regenerated.
Though the victim will at first appear otherwise unaffected from 628's attack, approximately five or more hours after they awake, they will transform into an experiment hybrid, depending on the DNA mixture from 628. The transformation is excruciatingly painful, and is apparently also permanent and irreversible.
628 has no apparent weakness and is virtually invincible. However, he can be destroyed through some method.