Stitch is the name of the genetic experiment 626, a fictional alien character from the Lilo & Stitch films and television program.
History
As revealed in Lilo & Stitch 2: Stitch Has a Glitch, Stitch was created by evil genius Doctor Jumba Jookiba with the genes of the galaxy's strongest and most ferocious creatures, but when the experiment was finished, Jumba was disappointed to see how cute and fluffy he was. Nevertheless, Jumba soon sees 626's destructive potential and begins to charge Stitch's molecules. However, before Stitch is fully charged, both he and Jumba are captured by police officers of the Galactic Federation.
626 is then sentenced by the Grand Councilwoman to life in exile on a desert asteroid and Captain Gantu escorts him. Stitch escapes and crash-landed in Kaua'i, Hawaii. Disguising himself as a dog, 626 was adopted by a little girl named Lilo, who names him "Stitch".
Stitch is trained by Lilo to be good, using Elvis Presley as a model for his behavior. Lilo's efforts prove to be fruitless at first, as Stitch is unable to suppress his destructive programming. Nevertheless, Lilo enjoys her new "puppy". Although at first he only wanted to use the girl as a human shield from Jumba and Agent Pleakley, whose mission is the capture the fugitive experiment, Stitch slowly develops feelings for Lilo, to the point where he saved her life from Gantu. After his heroics, the Grand Councilman allows Stitch to remain on Earth, citing Lilo's dog adoption certificate.
In Lilo & Stitch 2: Stitch Has A Glitch, Stitch is living well and is reasonably well-behaved (although still hot-tempered and mischievious) with the exiled Jumba and Pleakley in Lilo's house until he begins malfunctioning. Since he was not fully charged after his creation, Stitch experiences periodic glitches that have him reverting back to his original destructive programming. Seeing this, Jumba strives to create a proper charging chamber for Stitch. Not wanting to hurt anyone and not knowing about Jumba's plan, Stitch attempts to leave Earth for a remote planet, while Lilo, Jumba and the others desperately try to have him return so that can recharge him. Although they are too late when they place him in the recharging pod, somehow Stitch is revived by a grieving Lilo.
Afterward, in Stitch! The Movie, 626 discovers the remaining 623 genetic experiments locked in a crate, in the form of dehydrated pods. In order to rescue Jumba, Lilo and 626 institute a trade between Doctor Hämsterviel and Jumba for the experiments, but it instead results in the freedom of the experiments and the capture of Lilo and Stitch. Hämsterviel then tries to clone Stitch, in a process that would have most likely destroyed him but the previously activated Experiment 221 ("Sparky") interrupts the process by creating a power surge in order to shut down the cloning equipment. Stitch then rescued Lilo and landed Hämsterviel's spacecraft back in Kaua'i, where the Grand Councilwoman waited to arrest Hämsterviel.
In the subsequent television program Lilo & Stitch: The Series, Stitch resides in Lilo's house, continuing to disguise himself as a dog in order to conceal his identity from humans. Along with Lilo, he re-captures and rehabilitates Jumba's genetic experiments.
Abilities
Experiment 626 has a variety of special abilities. He is fire and water-proof and can also lift objects 3000 times his weight. A running joke throughout Stitch! The Movie and Lilo & Stitch: The Series being that he can't lift an ounce more than that. He also has very sensitive eardrums, that when exposed to loud noises can cause temporary deafness. His eyes can pick up infrared and ultraviolet light, as well as visible light and he can filter out one or the other if necessary. He also can act as an audio amplifier and/or microphone.
Disney Adventures
According to the Disney Adventures comic "Experiment 626", Stitch was created with the genes of the galaxy's strongest and most ferocious creatures, but somehow the genes of a puppy got mixed into the batch. Stitch was created using the so-called "Jumbatron 6000", apparently some kind of cloning or splicing device. After his creation, 626 was determined a failure and Jumba continued work on his next experiment. As shown in a deleted scene from Lilo & Stitch, 626 promptly proved Jumba wrong by causing various acts of mayhem, resulting in panic among the populous before the events of the first movie see him captured. However, it appears that this plot has been retconned, since in Lilo & Stitch 2 he is shown to have been captured before he is able to cause any further damage.