Stitch is the name of the genetic experiment 626, a fictional alien protagonist from the Lilo & Stitch films and television program. Originally created to cause chaos across the galaxy, he is marked by his short temper and mischievous behavior, traits that endear him to his friend Lilo, who adopted him as her puppy dog. He is voiced by his creator and the film's co-director, Chris Sanders.
Stitch is a blue alien genetic creation standing around 3 feet tall. He strongly resembles a koala, or a french bulldog, as he's referred to as a dog throughout much of the franchise. He has a limited ability to change his physical appearance, as he can retract a second set of arms, his antennae, his claws and the three spines on his back into his body.
As revealed in Lilo & Stitch, Stitch was created by "evil genius" Dr. Jumba Jookiba, who called him "Experiment 626", with the genes of the galaxy's strongest and most ferocious creatures being zapped with electricity to start the molecules forming and starting to solidify into the form and fully formed, but when the experiment was finished, Jumba was disappointed to see how cute 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 (Seen on a flashback on Lilo & Stitch 2: Stitch Has a Glitch).