Dr. Jacques von Hämsterviel is a diminutive alien scientist with a rodent-like appearance, featuring white fur, red eyes, a hamster-like body, a gerbil-like lower body, rabbit-like ears and face, and a cow-like tail. He is typically seen in a prison jumpsuit with horizontal blue stripes or a red cape with a golden "H" brooch. He is the former lab partner and financier of Dr. Jumba Jookiba, having funded the creation of Jumba's genetic experiments through shady business deals. After his imprisonment, he seeks to capture all 625 experiments, which he considers his property, to further his goal of galactic domination. He employs the retired Captain Gantu to capture the experiments, frequently subjecting him to verbal abuse and physical assaults for perceived failures. Hämsterviel exhibits a Napoleon complex, demonstrated by his intense desire for power despite his small stature. His personality is characterized as cunning, diabolical, self-absorbed, and abusive toward subordinates. He readily insults others and often behaves like a spoiled brat, throwing tantrums when his plans are thwarted, though he is also a coward when faced with direct conflict or danger. A recurring source of frustration is the widespread mispronunciation of his name, often as "Hamsterwheel" or "Hamsterveal," and he is frequently mistaken for a gerbil despite insisting he is hamster-like. His operations are frequently conducted from a sophisticated prison cell equipped with communication and teleportation systems, which can be hidden or revealed via a voice code. On one occasion, he was granted a furlough from prison, came to Earth disguised as a human, and nearly succeeded in reverting Stitch to his original destructive programming. His history with Jumba includes their time together at Evil Genius University and subsequently running a joke shop. Their partnership deteriorated due to Hämsterviel's cheating and stealing. Jumba initially believed Hämsterviel was dead prior to his appearance in Stitch! The Movie. In Leroy & Stitch, Hämsterviel escaped prison with Gantu's help and forced Jumba to create a new experiment, Leroy. He then created an army of Leroy clones to overthrow the Galactic Council. His plan was ultimately foiled when Gantu, motivated by spite over his abusive treatment, assisted Lilo and Stitch. Hämsterviel and his Leroy army were defeated and incarcerated in individual cells on Prison Asteroid K-37. Following these events, he was broken out of prison again by Gantu. In the Stitch! anime, he formed a partnership with a fearsome alien named Delia, whom he and Jumba had known long ago. His objective was to capture Stitch to utilize his power cell for creating a new, powerful experiment. He also stole several experiments previously left with the Galactic Federation and from Hawaii. He developed methods to revert experiments to evil, initially using Experiment 624 (Angel)'s song and later a transmutation process that altered their DNA and enhanced their abilities to bring them under his control. During this period, he created his own experiment, Skunkuna, and deployed it to cause havoc. Throughout his schemes, he has been personally affected by several experiments. He once suffered amnesia from a memory-erasing experiment, during which Gantu mocked him by inventing embarrassing false memories. On another occasion, he was pecked by a love-inducing experiment, causing him to develop romantic feelings for Gantu, though he continued to insult him as usual. He is an expert laser-sword duelist. His official phone number is 555-019-829-3434-533-65-5882, and he was held in Cell 750 at Prison Asteroid K-37 in the Xenon Sector. A brief cameo appearance occurs in Stitch & Ai, where he is seen breaking rocks on a volcanic prison planet when the Grand Councilwoman threatens Jumba with incarceration.