BooGoo is a mysterious alien creature in the Stitch! anime who is introduced at the beginning of the second season, Stitch! ~The Mischievous Alien's Great Adventure~. Although a self-centered indulgence, she is a pet that is loved by everyone present on the island, except for Stitch, who finds her annoying. She often accompanies Yuna, Stitch, Jumba and Pleakley on certain missions throughout the anime series.
According to the English dub, Hämsterviel met the little alien in the weight room on the prison planet that he, Gantu, and Reuben were sent to after the first season finale. Hämsterviel sends her to Izayoi Island on Earth to break Stitch's Good Deed Counter. After arrival in the nearby sea, the alien morphs into a mosquito, then finds Stitch with Yuna and Kijimunaa at latter yokai's tree. The little alien pecks at the counter's screen, causing it to glitch, and fly off. From there, Stitch finds that the counter has gone wrong, turning into a "bad deed counter"; whenever he does good deeds, the counter goes down, and whenever he does bad deeds, the counter goes up.
After Kijimunaa falls ill, Stitch decides to ditch the counter to help his friend. Jumba, however, decides to inspect the counter, and does find it to be glitching. However, Pleakley has also found the purple alien, mistaking the alien to be a new species of fruit fly. When the alien freaks out after sucking juice from a peach, Pleakley calls for Jumba to check on the alien.
After dealing with Pleakley's fruit flies, Jumba inspects the alien and finds that she was used by Hämsterviel as a slave, disabling a red collar with a letter "H" that was put on her as a controlling device. Soon thereafter, Jumba and Pleakley find Gantu having crashed his stolen spaceship on the island and attempt to steal the Spiritual Stone. Pleakley, sends out his fruit flies, including the purple alien, out to attack Gantu.
After Stitch and Yuna return with the fisheyes, feeding them to an ill Kijimunaa to heal him, Pleakley tells them about the purple "fruit fly" responsible for the glitch thanks to Hämsterviel. The "fruit fly" then morphs into her true form and flies around greeting Yuna and Stitch's ʻohana, repeatedly shouting, "BooGoo!" which the others assume to be her real name. From there on, BooGoo becomes part of the ʻohana.
In one episode, Experiment 303 (Amnesio) zaps the memories of BooGoo, Stitch, Jumba, Gantu, Reuben and Hämsterviel. Everyone's memory is shown to be stored in capsules under Amnesio's wings. When Amnesio is eventually captured, Gantu demands him to give up the memory-containing capsules. Near the end of the episode, it is shown that the capsule Gantu had swallowed didn't contain his own personality – it contained BooGoo's! Likewise, on Earth, Gantu finds himself in BooGoo's body and demands to be put back to normal.