Leroy

Leroy is the evil twin brother of Stitch who first appeared in Leroy and Stitch. In promotional material for the film, Leroy was also referred to as Experiment 628. However, this is false as he was only called Leroy in the film and is the doppleganger of Experiment 626. He was voiced by Frank Welker.

Leroy & Stitch
Leroy was the last of Jumba's experiments to be built. While spending a few years on Earth, he had an unfinished experiment at his laboratory in deep space. After Lilo and Stitch successfully captured all experiments and turned them from bad to good, Jumba regained access to his laboratory. During this time, Jumba's evil former partner Dr. Hämsterviel had escaped prison with Gantu's help.

Jumba started creating an experiment with explosive saliva from a similar template to Stitch until he was forced by Hämsterviel (who paid Jumba a visit) to instead make the latter "a new version of 626." Forced to comply, Jumba created a red, destructive replica of Stitch, and Leroy was born. Shortly after, Stitch attacked the lab, and Leroy was released to battle Stitch. After a long fight ensued between the twin experiments, Stitch had Leroy pinned down, but Pleakley's untimely arrival distracted Stitch long enough for Leroy to bat Stitch into a containment orb.

Leroy proven to be more powerful than Stitch, he was then cloned by Hämsterviel into an army.

The original Leroy then took over the BRB by posing as Stitch, the captain, and ordered that the pilots take him, Hämsterviel, and the Leroy army to Turo.

En route, Leroy recieved a call from Lilo, and, resuming his Stitch disguise, attempted to pose as Stitch. However, he was quickly discovered by Lilo to be an imposter, causing Hämsterviel to order Leroy to "hang up" (namely by blasting the communicator).

Meanwhile, a Leroy clone arrived on Earth, where it rounded up all of the first 624 experiments there (along with Mertle Edmonds while capturing Gigi) and brought them to a stadium to be destroyed.

Upon arriving on planet Turo, the Leroy army was able to overthrow the council and gain galactic domination.

Shortly after, Hämsterviel, and the entire Leroy army arrived at the stadium on Earth in the BRB to destroy the captured experiments. Before they could, however, Lilo, Stitch, Jumba, Pleakley, Reuben and a reformed Gantu arrived and a battle ensued between the experiments and the Leroys. Though the experiments were able to overpower the Leroys at first, the Leroys soon gained the upper hand.

However, as the Leroys came close to winning the battle, Lilo, Stitch, Reuben and several other experiments performed the song Aloha Oe, which caused all the Leroys to shut down due to the original's failsafe.

All of the Leroys were then sent to prison on Asteroid K-37, where they were seen happily dancing to the song "Jailhouse Rock" with an angry Hämsterviel tapping his feet.

Trivia

 * In spite of Leroy and Stitch being Leroy's only media role, he continued to appear in a number of merchandise, popular in Japan.