Jumba was born on the planet Kweltikwan. There, he created a series of illegal genetic experiments, but was eventually banished as a result. He then bought his own laboratory, where he continued to create more experiments alongside his former college friend Dr. Hämsterviel, where the two both graduated from Evil Genius University and managing a business called Jokes on You. Eventually, both Jumba and Hämsterviel would be arrested, following the creation of Jumba's latest experiment, 626. However, this new experiment proved to help Jumba in more ways than one, having him released from prison and finding him a family that loves him and vice versa.
He is said to be divorced and has mentioned his ex-wife several times (usually in a negative way). However, he has a stronger respect for his mother.
Jumba is a comical and endearing character, despite his "evil" status. Prior to meeting Lilo, Jumba was somewhat insane and ruthless, engaging in illegal, genetic experimentation, for the sole purpose of wreaking havoc across the galaxy. The motivation towards such malice remains unknown, though his previously sadistic nature hints it was merely for his own evil satisfaction and enjoyment. He's more interested in anarchy and chaos rather than true evilness.
Interestingly, Jumba's switch from villainous to heroic was rather hasty, showing he apparently had some form of moral to him even before meeting Lilo, as he quickly agreed to rescuing her after she was wrongfully captured by Captain Gantu, in an attempt to capture Stitch. Upon meeting Lilo, and following his welcome into the Pelekai family, Jumba became rather humble and began to act as a father-like figure towards Lilo, his previously egotistical nature watering down to mere pride and confidence, and his villainy forming into innocent mischief. He is often paired with his friend Pleakley, who was forced to work alongside him to capture Stitch when he was still a menace. The two had a bitter relationship at first, but following the events of the original film, Jumba and Pleakley became the closest of friends.
Ironically, for an evil genius, Jumba is actually very friendly and sociable outside his work. He is also one of the few characters, aside from Lilo, Nani, David, Pleakley, and most of the other experiments, who loves Stitch. In fact, Jumba loves all of his creations, having a sense of paternal pride in them. He also speaks with a vaguely Russian accent, but ironically uses very poor grammar. This is not what one would expect from an evil genius scientist.
Though the extent of Jumba's "genius" can be somewhat questionable at times, the scientist proves to be a mastermind in his own right, as well as generally, having the ability to create new, sentient lifeforms singlehandedly, as well as a slew of different creations, as seen in the animated series, though they can sometimes cause more havoc than initially intended, even if their purpose was to enhance life's fortunes, rather than cause mayhem.
Jumba is a large, obese, hippo-like alien who wears a prison jumpsuit covered in horizontal dark and light blue stripes when he was imprisoned. In his "evil genius" form, he wears a white lab coat and sometimes a white wig. In his "Lilo's uncle" disguise, he wears a yellow (sometimes light blue) Hawaiian shirt with a couple of black vertical buttons and red (or white) Hawaiian designs on it, blue shorts with white linings, and gray boots with light gray soles.