Leroy a.k.a. Experiment 629 is an illegal genetic experiment and the main antagonist of Leroy & Stitch. He is Stitch's evil twin, and has an army of clones. He is designed to have all of Stitch's powers, but he also has the ability to disguise himself as Stitch by changing his fur color from red to blue and instantly regrow his fur. He is Dr. Hämsterviel's new henchman and own version of Stitch. His one true place is in prison.
Like Stitch, Leroy is voiced by Chris Sanders, while his growling is provided by Frank Welker.