Dr. Rupert Jacques von Hämsterviel

Dr. Jacques von Hämsterviel is a main antagonist of the Lilo and Stitch franchise. Hämsterviel's first major appearance was in the film Stitch the Movie! where he begins his plans to take over the galaxy. Hämsterviel is the former partner of Jumba Jookiba who later becomes one of his enemies. He is voiced by Jeff Bennett.

Background
Before the events of the franchise, Hämsterviel worked alongside Jumba Jookiba as scientist. Together, they made genetic illegal experiments. According to Jumba, it was Hämsterviel that went to the authorities about the illegal experimentation. Hämsterviel was more than likely arrested as well because of the heavy affiliation. Oblivious to Hämsterviel, Jumba was released to capture his latest experiment 626. During these events, Jumba reformed and spent his days on earth with a new family. Eventually, Hämsterviel would escape, recruits the former captain of the Galactic Federation as his henchman, and seek to regain "his" experiments. Hämsterviel's attempts failed but the constant failures did not prevent the mad scientist to trying again. Years after these event, Hämsterviel sets out to harvest absolute power instead.

Personality
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.

He is cunning, diabolical, and very abusive to his employee, Gantu, whom he frequently assaults with a plethora of poorly-sarcastic insults but nevertheless demeaning. He doesn't care about his minions so long as they serve him competently but 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, he didn't need Gantu.

Hämsterviel also hates his old business partner, Jumba, as well as Stitch, Lilo, Pleakley, and later, Yuna. His schemes have sometimes been directed at them, either to enslave them, or even kill them. Originally, he schemed to take the 625 experiments Jumba created before Stitch, and use them in his bid to conquer the galaxy, viewing the experiments as his own property because he financed their creation using his shady business deals.

Lilo & Stitch
Hämsterviel had a small non-speaking cameo around the start of the film when Pleakley and the Grand Councilwoman make way for Jumba's jail cell. However, this was a mere background appearance with no significance whatsoever.

Stitch! The Movie
Hämsterviel appears as the main antagonist of the film, setting up his role for the rest of the franchise. Here, with his new associate Gantu, Hämsterviel plots to take over the galaxy by using the power of Jumba's 625 experiments who have been podded since Jumba's arrest. He orders Gantu to find the pods which are located in Jumba's room in Hawaii. Once the experiments are captured, Lilo and Stitch head over to Gantu's ship before the plan can be complete. Lilo is captured as well as Stitch. While Lilo is put into a cell, Hämsterviel plots to cut Stitch in half via laser. However, Stitch breaks free and traps Hämsterviel onto the platform. After Lilo's rescue and a scuffle with Gantu, the experiments are accidentally released on Hawaii. With Hämsterviel under arrest, Lilo and Stitch prepare a hunt for each experiment, with the exception of 625 who Hämsterviel unleashed thinking he would be another Stitch power wise, but instead, he was a lazy sandwich maker.

Lilo & Stitch: The Series
Hämsterviel currently resides at the Galactic Prison where in his cell communicates with his sidekick Gantu. He constantly appears on screen in Gantu's home berating him and scolding him about his endless line of failures. On occasion, he has escaped prison and went to earth. In one episode, he accidentally became the pet of Lilo's rival, Mertle. Eventually, he has grown to like her and is currently her only friend.

Leroy & Stitch
In Leroy & Stitch, Hämsterviel escapes prison and forces Jumba to create a new experiment, which the former names Leroy. He then repeatedly clones Leroy and uses the clones to take over the Galactic Alliance, firing Gantu afterward for his incompetence. This proves to be the key to his downfall, as Gantu breaks Lilo and 625 out of prison. When Hämsterviel goes to watch Leroy and his clones destroy the other experiments, his plan is thwarted by the arrival of the reformed Gantu, Lilo, Stitch, Reuben, Jumba, and Pleakley, who team up with all the other experiments and defeat Leroy. After Lilo, Stitch and Reuben defeat all of the Leroy's with Aloha `Oe, the remaining angry experiments toss him around like a beach ball causing him to yell, "I am not beach ball-like, I am hamster-like!" Hämsterviel is sent back to prison afterward, with all the Leroys in the cells around him.

Stitch! anime
In the anime series, Hämsterviel plots against Yuna and Stitch alongside his lackeys Gantu and 625. Unlike the previous series, Hämsterviel frequently goes out into the open to take control over Stitch. In this show, Hämsterviel plots to become the most powerful being in the universe, thus giving him the advantage of taking over the galaxy with ease. In one special episode entitled Stitch Vs. Hämsterviel, his goal was completed but ended after an epic battle with Stitch. A running gag in the series includes several characters mistaking Hämsterviel for a mouse-like creature as opposed to a hamster-like. This gag echoes the previous misconception of Hämsterviel being a gerbil-like creature.

Disney Parks
Dr. Hämsterviel appears as a walkaround only at Tokyo Disneyland along with many other characters from the franchise, as the film and television series are some of the most popular Disney media in Japan. Hämsterviel also made an appearance in Disneyland Paris as part of Stitch's Hawaiian Paradise. Hämsterviel is also seen atop a float in the parade Lilo and Stitch's Big Panic: Find Stitch.

Midsummer Night's Panic
At Tokyo Disneyland, Hämsterviel plots to finally capture Stitch and steal his powers. When his minions locate him, they travel to Earth to make the move. Hämsterviel sends Gantu to proceed with the capture, but the bumbling captain fails and joins Lilo and Stitch's party instead. After all seems lost for the villains, Hämsterviel arrives but decides to join as well with no minions to assists him with the plans.

Trivia

 * In the first film, a Hämsterviel look-alike can be seen in one of the prison cells on Asteroid K-37.
 * 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.
 * Despite the word "hamster" in his name, Hämsterviel actually looks more like a gerbil than an actual hamster. This ironically reinforces the fact that he actually hates being called a gerbil.
 * 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.
 * It should be noted that when Hämsterviel speaks, he uses ambiguous language.