Dr. Jacques von Hämsterviel is a diminutive, rodent-like alien scientist with white fur, piercing red eyes, long rabbit-like ears, prominent buck teeth, and a tail featuring bushy brown fur. He always wears a distinctive red cape fastened with a gold "H" brooch. He vehemently insists he is "hamster-like," constantly correcting anyone who calls him a gerbil or mispronounces his name as "Hamsterwheel" or similar variations. He is the former partner of Dr. Jumba Jookiba. Together they co-founded "Jokes on You" and graduated from Evil Genius University. Hämsterviel financed Jumba's creation of 625 illegal genetic experiments through shady business deals, viewing them as his exclusive property. He later betrayed Jumba by alerting the Galactic Federation, resulting in Jumba's arrest. Though imprisoned himself, Jumba believed Hämsterviel dead until his surprise reappearance. Hämsterviel's driving ambition is galactic domination, specifically aiming to use the experiments to overthrow the Galactic Councilwoman and seize control of the Galactic Federation. Driven by a Napoleon complex, Hämsterviel compensates for his small stature with a domineering, volatile, and self-absorbed personality. He frequently hurls insults, targeting even his former partner Jumba and his long-suffering henchman Captain Gantu, whom he abuses both verbally and physically. He exhibits no loyalty, readily discarding minions like Gantu once they seem useless—a flaw that ultimately leads to Gantu defecting to aid Lilo and Stitch, contributing to Hämsterviel's downfall. Despite his bravado, he reveals cowardice when directly confronted, such as being caught in his own restraints or facing vengeful experiments. After escaping prison in *Stitch! The Movie*, he hired Gantu to capture Jumba's scattered experiments. His attempt to clone Stitch failed, dispersing experiments across Earth. In *Leroy & Stitch*, he forced Jumba to create Leroy, a red Stitch-like experiment, cloned him into an army, and briefly conquered the Galactic Federation. His victory crumbled when Gantu helped Lilo and Stitch deactivate the Leroy clones using "Aloha ʻOe." Hämsterviel was re-imprisoned, though later freed by Gantu. In the *Stitch!* anime continuity, Hämsterviel partnered with Delia, a formidable alien known to him and Jumba years earlier. He stole experiments from both the Galactic Federation and Hawaii, repurposing them to capture Stitch. Utilizing Angel's song and DNA transmutation, he reverted experiments to their evil states, sometimes altering their abilities or appearances. He also engineered his own experiment, Skunkuna, to cause chaos. His schemes continued relentlessly, focusing on exploiting Stitch's power cell to forge a new super-weapon. Throughout his appearances, Hämsterviel's background includes fleeting moments of camaraderie with Jumba, revealing a jokester side. Newspaper archives show him waving his posterior at Jumba during their early collaborations. His later actions, however, are defined by relentless ambition, cruelty, and repeated defeats, often triggered by his mistreatment of allies and overwhelming overconfidence.