TV-Series
Description
Dr. Jacques von Hämsterviel is a diminutive, rodent-like alien scientist sporting white fur, piercing red eyes, prominent rabbit-like ears, buck teeth, a pink nose, and a long tail tipped with bushy brown fur. He invariably wears a distinctive red cape secured by a gold "H" brooch. Though he self-identifies as "hamster-like," he is frequently mistaken for a gerbil or rabbit, a source of constant irritation.

Originally the lab partner of Dr. Jumba Jookiba, the pair graduated from Evil Genius University and initially operated a business named "Jokes on You" before turning to illegal genetic experiments. Hämsterviel funded these ventures through undisclosed "shady business practices," while Jumba provided the scientific expertise. Hämsterviel ultimately betrayed Jumba by alerting the Galactic Federation, resulting in Jumba's arrest and Hämsterviel's own imprisonment. Jumba believed him dead until his eventual reappearance.

His core motivation is galactic domination. He claims ownership of Jumba's 625 genetic experiments due to financing their creation and aims to exploit their power to overthrow the Galactic Federation's Grand Councilwoman. After escaping prison, he recruits the exiled Captain Gantu as his henchman to capture the experiments scattered across Earth.

Personality-wise, Hämsterviel exhibits a Napoleon complex, compensating for his small stature with grandiosity, ruthlessness, and a volatile temper. Profoundly self-absorbed, he considers no one his equal and habitually insults others, including Gantu and Jumba. He is verbally and physically abusive toward Gantu, demeaning him for failures and showing no gratitude for successes. This persistent mistreatment eventually drives Gantu to defect and aid Hämsterviel's enemies. Despite his bravado, he displays outright cowardice when directly threatened or rendered helpless, such as when trapped by Stitch or confronted by vengeful experiments.

In later appearances within the anime continuity, Hämsterviel forms an alliance with Delia, a fearsome alien from his and Jumba's past. His objective shifts to capturing Stitch to extract his power cell for creating a new experiment. He steals numerous genetic experiments from the Galactic Federation and Hawaii, then employs Angel's song and a transmutation process to "re-evil" them, altering their DNA to enhance abilities or change appearances and ensure obedience. He also creates his own experiment, Skunkuna, deployed to cause havoc. Additionally, he manipulates BooGoo, a small shapeshifting alien, to disrupt Stitch's activities.

Recurring traits include extreme irritation at the mispronunciation of his name (often as "Hamsterwheel" or "Hamsterveal") and fury at being labeled gerbil-like. Historical newspaper clippings reveal a more mischievous side during his early partnership with Jumba, involving pranks.

After numerous failed schemes, including an attempt to conquer the galaxy using an army of Leroy clones (a red, enhanced duplicate of Stitch), he is defeated and re-imprisoned. In custody, he continues plotting, shown in a cameo breaking rocks on a volcanic prison planet.