(EDITOR'S NOTE: Oh god this was a mess. Currently working on a re-write. Someone needs to clean up that Gumball page too, it's even worse than this one was.)
Lilo is one of the titular characters of Lilo & Stitch, a 2002 Disney movie. In the movie, she finds an alien creature, who she adopts and names "Stitch". However, the two are hunted down by other aliens, who created Lilo's newfound pet as an instrument of destruction, and now want it back.
The original movie had two sequels. One was a DVD movie in 2003, and the other a TV movie in 2006. As with all Disney DVD sequels, these are somewhat of a drop in quality from the original.
Lilo was a main character in all three movies, as well as an animated series lasting from 2003 to 2006. She had no further appearances afterward, but Stitch would go on to star in two more shows produced for the Japanese market.
There were rumors of a remake on Disney Plus, but nothing seems to have come of it. For now, the franchise remains dormant.