Lilo & Stitch is one of the Disney Animated Canon's most unconventional franchises, having been going along its own path since Chris Sanders and Dean DeBlois made the 2002 original film. This has led it to become an Ensemble Dark Horse unto itself within the DAC. Of course, one of this franchise's strong suits (and a reason for its success) is its unique and unconventional characters, many of whom became Ensemble Dark Horses in their own rights.
Lilo & Stitch: The Series pilot Stitch! The Movie, the experiments as a whole became such Ensemble Dark Horses that they became the biggest defiers of Disney's tradition of not acknowledging the sequel material of Walt Disney Animation Studios films in their works. Part of it may have to come from their Ugly Cute designs or for being Disney's version of Pokémon in a way.
- Prior to her ascension to major character status via the anime and merchandise, Angel (X-624) was this (and technically still is if you're from the United States where the anime flopped) since she only appeared in two episodes (plus a cameo in a third) and a few minor scenes during the final act of the last film.
- Sparky (X-221), likely because of his role in Stitch! The Movie, his powers, and for being Ugly Cute. He was even popular enough to be a mandatory Boss Battle in Kingdom Hearts: Birth by Sleep, making him the first Disney Television Animation character to appear in the Kingdom Hearts franchise. He also received several recurring appearances in the anime, was made into a costumed character for the Disney Theme Parks, and is even the only "cousin" to appear on this mural in Hanapepe◊—the town that inspired Lilo & Stitch's Kokaua Town.note
- Experiment 627, or "Evile" as the fans call him, due to the appealing concept of a tough experiment who's better than Stitch, and who would have likely become a rival to him had he received more appearances. He was number five on the aforementioned top ten poll and was also made into a Disney Parks costumed character.
- Bonnie (X-149) is one due to her Tomboyish personality, appealing design, Outlaw Couple dynamic with Clyde (X-150), and the fact that she's the only other prominent female experiment besides Angel whose body bores similarities to Stitch's.
- Splodyhead (X-619) seems to also be one, considering his fight against Slushy (X-523) in that experiment's episode (and the extensive reuse of scenes from that fight in "Ace") and his cameo in Big Hero 6, which made him the very first character from a sequel series to a DAC film to appear in a later DAC film.
- Felix (X-010) is one due to his cute looks and hilarious obsession with cleaning as "Felix" or spreading dirt as "Oscar". Even the way he says "Dirty!" is oddly adorable. He even made a few more appearances in the anime, was also made into a costumed character for the Disney Parks, and is even the only playable character outside of the mid six-twos in the Nintendo DS game Disney Stitch Jam.
- Slushy (X-523) due to the surprisingly wide range of abilities he shows from his ice-generating powers (as seen in his aforementioned fight with Splodyhead) and for his playful trickster personality. (In fact, he actually has one of the more fleshed-out personalities among the experiments.)
- Yin (X-501) and Yang (X-502) for their Opposites Attract dynamic. In fact, these two were seventh on that top ten poll.
- Sample (X-258) is a peculiar one for his upbeat, carefree attitude and ability to provide some fresh beats with the sounds he records. He too received a costumed character counterpart for the Disney Parks.
- Of all the experiments that were introduced in Leroy & Stitch, Carmen (X-123) got the most attention due to her fun Carmen Miranda-inspired design and visual similarities to Angel. We didn't get to see what her ability was in the film, but thankfully, she eventually appeared in an episode of Stitch! ~Best Friends Forever~ and was given an ability that fits her very well.
- Bragg/Flute (X-145) or Twang (X-023) — a.k.a. that yellow cat/rabbit-like flute-playing experimentnote — only appeared in one episode of the Stitch! anime, but he's by far the most popular experiment who was introduced in (and remains exclusive to) that show. The anime's fans were won over by his wickedly deceptive personality underneath his charming exterior.
- Houdini (X-604) is one for his adorable looks with big eyes and ears on a small rabbit-like body combined with his Lovable Coward personality.
- Spike (X-319) is liked for his porcupine-like design and the way he was reformed with a therapeutic hug, which caused him to turn to giving hugging therapy to calm down truant experiments as his "one true place" (even though he has to wear armor to do that). Helps that his episode is seen as one of the best episodes of the entire series.
- Despite originating from the anime, and that they were not created by Jumba, but rather the disliked third season antagonist Delia, Dark End is surprising liked for their Affably Evil personality and adorable looks with big ears and a small pink nose.
- Ice Cream Man. So much that he was the only Lilo & Stitch character other than Lilo, Stitch and Nani to be made into a Townsperson costume in Disney Infinity, where he costs 100,000 blue sparks in 2.0's Toy Store.
- Lilo's doll Scrump is not even alive (save for that one time Phantasmo possessed "her") and only plays a small role to Lilo's character, but "she" gets a lot of fan art and merchandise (albeit, oddly appearing with Stitch more than with Lilo instead), which even includes a couple Funko Pop! vinyl figures modeled after "her". The best evidence supporting this has to be in this official fan art contest held by Disney and BoxLunch (Hot Topic), where Scrump appeared on eight of the twenty-five chosen finalists for the contest (tied with Lilo as the second-most appearing character), six of which feature only "her" and Stitch together.note That said, her over-prominence in merchandise—often, as aforementioned, with Stitch and without Lilo—combined with a seeming dearth of merch featuring characters other than her and Stitch, has caused a number of core fans to resent the doll, making "her" a Base-Breaking Character nowadays.
- Amy Hill as Mrs. Hasagawa is a very memorable character even if she appears only once in the original film. Thankfully, The Series gave her a few more appearances, including involving her in a B-Plot of the American Dragon crossover episode and even making her the focus of half of a Two Shorts episode.
- The blonde lifeguard whom Nani briefly talks with for a job is extremely popular, for some strange reason.