Captain Gantu is Lilo and Stitch's former archenemy, serving as the main antagonistic anti-hero in the original film and later evolving into a true villain in the animated series, and eventually teaming with Lilo and Stitch on the hero side during Leroy & Stitch.
An extremely large and muscular alien with a gruff, militant personality, Gantu resembles a bipedal whale with grey skin, sky blue eyes and elephant-like feet, wearing a black battle shirt and black pants and stands 20 feet tall. When he is seen by humans on Hawaii, he typically attempts to pass himself off as a Samoan, though Lilo once told Mertle he was a dogcatcher from Nairobi, which the other girl believed. Lilo calls him "Big Dummy" for most of the series.
Gantu appreciates his position of authority amongst the military forces of his world, but his great size and superhuman strength often lead him to underestimate those smaller than he is. He shows no tolerance for failure, ensuring that underlings do as they're told. Additionally, Gantu demonstrates a great loyalty to the Grand Councilwoman, as he displays equally powerful negative feelings towards Experiment 626 and other experiments.
Serving no one besides the Grand Councilwoman and (to an extent) himself, the Captain of the Galactic Armada defends his ranking through any means possible, even aggression. Despite Gantu's intentions, whether they be good or bad, personal relations between himself and others, as well as his own jealousy and greed, often lead him into trouble.
Gantu was once the captain of Galactic Federation but failed to capture Experiment 626 (a.k.a. Stitch) after his escape from Turo (and after Jumba and Pleakley failed to catch him themselves). Forced by the Grand Councilwoman to retire, Gantu embarks on his new quest to capture all of Jumba's 625 experiments under the command of his new boss, Dr. Jacques von Hämsterviel, to use for galaxy domination.
Gantu is later met up with Experiment 625 (named Reuben by the end of Leroy & Stitch), who has all the same skills and abilities as Stitch but reduces himself to making sandwiches. Gantu is continually taunted by 625 for the many failed attempts to capture the rest of Jumba's 624 experiments (due to his record of only catching some experiments and keeping very few).
By the end of the series and ending with Leroy & Stitch, Gantu is fired by Hämsterviel for his countless failures. Gantu soon realizes he was in the wrong and helps Lilo, Stitch, Jumba and Pleakley stop Hämsterviel and his Leroy clone army. After the success of this mission, Gantu is offered his job as captain again by the Grand Councilwoman. Gantu accepts and requests Reuben to be his first mate and galley officer.
- "The Asteroid"
Gantu is a whale-like, grey-skinned alien who towers over most beings. He is also extremely muscular with a perfect and very humanoid body. Dressed in a sleeveless, black captain's uniform that has red lining on the uniform's shirt and trousers, this uniform includes a small gold badge, which Gantu pins to the left side of his chest. He also wears black gauntlets over his wrists. Gantu has three fingers on each hand and elephant-like feet with three very short toes and black toenails on the end. His head has some fish-like qualities, an example being a "dorsal fin" on the top of his head's center and a noseless face. Twin, fleshy, curved "tusks" also protrude from either side of Gantu's head. His teeth are quite small and come to a slight point. Gantu lastly has slanted blue eyes that lack pupils. A teal holster, strapped to a belt around his waist of the same color, holds his blaster when it's not in use.
Gantu lacks any notable abilities, but his immense stature (he stands around 20 feet, though he is noticeably shorter in the series than in the original movie) means he has strength well above any human (or most alien species), albeit sufficiently less than Stitch and at one point lost a wrestling match to an old lady named Suga Mama from The Proud Family.
Aside from his lifting capacity and enormous girth, Gantu is a respected captain of the Galactic Federation (or at least he used to be), can dance the hula (as seen in the episode "Clip") and does have many skills. He is depicted in the movie being a very capable spaceship pilot, having marksman-like shooting skills and competent leadership abilities. In Lilo & Stitch: The Series, Gantu relies primarily on his plasma pistol for combat. Besides firing plasma bolts, Gantu's pistol can also launch nets for capturing experiments.
Gantu has invented a "trog call" to capture experiments more easily (as shown in the episode "Frenchfry").
- Gantu is an expert in 12 martial arts.
- Gantu doesn't appear to be evil in the first film. However, it is completely unknown why he captured Lilo together with Stitch. It was probably unintentional, but he had no qualms with abducting her alongside Stitch (his primary target), and then didn't bother to release her.
- Gantu appears, along with several other Lilo & Stitch characters, in a parody of the Disney Channel Original Movie High School Muscial, which was broadcast as part of the High School Musical: Around the World one-year anniversary special.
- Gantu is mean and hostile due to his intellectual memory. This is proven when he loses his memory in the series episode "Amnesio" because he becomes very kind at once.
- Gantu seems to dislike working for Hämsterviel, and has occasionally done hostile things to him on purpose, which proves Gantu is not always on Hämsterviel's side.
- People mistake him as a whale or shark, due to the fact that he resembles a bipedal whale or shark. He has also been mistaken as a Samoan (due to his large size and when he is wearing human clothing).
- Despite claiming to not like the planet, Gantu seems to enjoy recreational activities on Earth. He danced at a luau in "Clip", showed an interest in kickboxing in "Kixx", enjoyed a spa weekend in "Fibber", played checkers and basketball in "Slugger", bought a boat to become a captain in "Shoe", watched Macki Macaw on TV in "Snooty", went surfing in "Phoon", played cards in "Ace", and sang karaoke in "Nosy" and "Snafu".
- His favorite kind of sandwich is egg salad as mentioned in Stitch! The Movie and Leroy & Stitch. However, he states in Stitch! The Movie that he dislikes bologna because it is too fatty.
- It has also been mentioned sporadically throughout the series and in the episode "Richter" that he is shown to like toasted bacon and raisin, as well as chicken soup sandwiches in "Slushy", "Poxy", and "Slick".
- However, he states in "Frenchfry" that he dislikes sweets, yet he devoured a whole cake that Frenchfry made him, which caused him to bloat up. On the other hand, this could be attributed to Frenchfry's ability to make food irresistibly delicious.
- In "Wishy-Washy", Gantu had a school year hologram, which is similar to a school yearbook; he was a member of an unknown football team and had a girlfriend named Cynthia.