Dr. Jacques von Hämsterviel is a major antagonist of the Lilo & Stitch franchise, becoming so after the events of the original film and its sequel. He is Gantu's boss and the former partner of Jumba Jookiba, who later becomes one of his main enemies.
Hämsterviel seems to have a bit of a Napoleon-complex, as despite his short stature, he has a large, imposing character and wants nothing less than total galactic domination, as he is extremely self-absorbed, viewing no one (not even his former partner Jumba or his henchman Gantu) as his equal. He insults everyone he sees, even when they do something for him or haven't done anything at all. Not to mention, he often acts like a spoiled brat, throwing a tantrum when he doesn't get his way, and will take his frustration out on anyone.
He is cunning, diabolical, and very abusive to his henchman Gantu, whom he frequently assaults with a plethora of poorly-formed, albeit demeaning and redundant insults (which could hardly even be called insults) for his failures to capture the experiments; even when Gantu manages to capture a few experiments, Hämsterviel never thanks him for it. He also doesn't care about his minions, so long as they outlive their usefulness to him. However, despite Gantu's loyalty, as well as helping him escape jail in Leroy & Stitch, he promptly fired Gantu after Hämsterviel's objectives had been achieved, saying that since he had Leroy to do a better job, Gantu was of no use to him anymore. This horrible treatment was one of the things that proved to be his downfall, as Gantu would later help Lilo and Stitch into defeating Hämsterviel out of spite against him.
Hämsterviel also hates his old business partner Jumba, as well as Stitch, Lilo, and Pleakley. His schemes have sometimes been directed at them, either to enslave them or even kill them. Originally, he schemed to capture the 625 experiments that Jumba created before Stitch and use them in his bid to conquer the galaxy, viewing them as his own property because he financed their creation using his shady business deals.
In spite of Hämsterviel's diabolical nature, he's shown to be a coward in the face of danger, he only shows it if he ever faces conflict himself or caught in a helpless situation that puts him in the face of death. After Sparky freed Stitch, the two restrained him in the same restraints he used on Stitch to slice him in half, prompting him to say that it was joke. This was shown again after Leroy and his clones were shut down, Hämsterviel got nervous when he was left alone and defenseless at the angry 623 experiments.
Back in the years, when he and Jumba were friends, Hämsterviel was shown to be somewhat of a jokester. In three newspaper articles of their graduation, business, and their first experiment, Hämsterviel was waving his posture at him.
Hämsterviel is a diminutive albino alien scientist who desires to conquer the galaxy. He has a rodent-like appearance with white fur, red eyes, a hamster-like body, a gerbil-like lower body, a rabbit-like face, rabbit-like ears, and wears a red cape with a golden "H" brooch on the front.
Because Dr. Hämsterviel was imprisoned, he wears a prison jumpsuit covered in horizontal dark and light blue stripes. The former lab partner of Dr. Jumba Jookiba, he now seeks to capture the genetic experiments he helped to create through financing, with the help of the retired Captain Gantu, before Lilo and Stitch. The few times Gantu is able to capture an experiment are coupled with comedic moments, usually at the expense of Hämsterviel.
Much to Hämsterviel's chagrin, a vast majority of the universe mispronounces his name, usually as Hamsterwheel or Hamsterveal, but on some occasions, other variations have been used, such as Gerbilviel. He is also often mistaken for a gerbil-like creature, despite his insistence that he is hamster-like (though due to his long ears, buck teeth, and triangular nose, he looks more like a rabbit).
Hämsterviel usually works from his "prison cell" which he has set up to be a laboratory, complete with communication and teleportation systems, and can be revealed or hidden using an encrypted voice code. During one furlough from prison, he came to Earth and, disguised as a human, tried to trick aliens into working for him. He managed to fool Stitch and nearly reverted him to his evil destructive programming. Several times, Hämsterviel has been personally affected by some of the experiments. On one occasion, he suffered amnesia from a memory-erasing experiment, and Gantu mocked him by making up embarrassing lies to fill in the blanks. Another time, he was pecked by a love-inducing experiment that caused him to fall in love with Gantu, although he still insulted him like he would on a regular basis.
In Leroy & Stitch, he was broken out of his cell by Gantu. He then used Gantu to force Jumba to create a red version of Stitch named Leroy. Hämsterviel then cloned Leroy into a huge army, and together they overthrew the Galactic Council. In the end, Hämsterviel and his Leroy army were defeated and taken back to Prison Asteroid K-37, where they were all put in individual prison cells.
- At the start of Lilo & Stitch, a Hämsterviel look-alike briefly appears in one of the prison cells while Pleakley and the Grand Councilwoman make their way towards Jumba's jail cell. However, this was a mere background appearance with no significance whatsoever.
- Hämsterviel's design is likely to have been inspired by Dr. Habbitrale, a villain from the video game Disney's Stitch: Experiment 626. Within the Lilo & Stitch universe, it is likely that they are the same species.
- In the Polish dubs of the Lilo & Stitch franchise, his name changes from Chomikviel (meaning literally "Hämsterviel") to Chomikvader (Hämstervader), which is an obvious reference to Darth Vader. However, Hämsterviel is referred to as Chomikviel in the series only, and as Chomikvader in a majority of other media.
- He is perhaps the most significant villain related to the Disney animated canon to not feature in the original film of his property and only appear in sequel media.
- Hämsterviel is an expert laser-sword duelist.
- Hämsterviel's phone number is: 555-019-829-3434-533-65-5882.
- His prison in Xenon Sector: Prison Asteroid K-37 is Cell 750.
- Hämsterviel is a play on the term "hamster wheel", an exercise decoration commonly placed inside most hamster enclosures.
- This is actually a running gag throughout the franchise, as his name is usually mispronounced as "Hamsterwheel".
- It is unknown if Hämsterviel's accent is supposed to be either French or German, since "Jacques" is obviously French (the equivalent of "John"), and "Hämsterviel" is clearly German-sounding with an accent over the "a" in his last name.
- Accent wise, he sounds like one of the French knights from Monty Python and the Holy Grail, but uses ambiguous language when he speaks.
- Hämsterviel's quote: "No prison can contain me!" is similar to Boris the Animal's line from Men in Black III.
- Many other characters mistake him for a gerbil-like creature or a rat-like creature given his appearance, though he insists that he is hamster-like. However, despite this, and the fact that he has the word "hamster" in his name, Hämsterviel actually looks more like a rabbit than a gerbil or hamster.
- He also resembles a rabbit with albinism due to his bright red eyes and almost complete lack of pigmentation in his fur, although it is unknown if he suffers from the condition himself.
- After the events of Leroy & Stitch, Hämsterviel was freed by Gantu. It was also revealed in the Stitch! anime that Hämsterviel partnered with Delia whom he and Jumba met long ago in "Stitch's Birthday: Part 1".
- Hämsterviel appears in the online game Lilo & Stitch: Alien Interception along with Plasmoid, Tank, Dupe, Clyde and Yang.