Supai was going to be the ancient Incan god of Death who was sealed away by the other gods long ago when the world was created, as the other gods wanted to allow the light to reign on the land, something which Supai was against, as he wanted to unleash darkness over it. To do so, the other gods created the sun.
Years later, the Incan necromancer Yzma, with the help of her reanimated mummy henchmen Mick, Bowie and Lemmy, determines to use her dark magic to not only gain control over the kingdom of Emperor Manco but to summon Supai so he can block out the sun unleash everlasting darkness over the world, blaming the sun for aging her and desiring to live in a dark world where she cannot age any further.
During the film's climax, Yzma succeeds in summoning Supai, who tries to block out the sun as he had wanted to do years ago. However, Pacha, Manco and Nina arrive and fight against Supai's powerful forces. Fortunately, the heroes ultimately win when Pacha is granted a magic lasso by the other gods, lassos the sun, and brings it down on Supai, destroying him and ending his threat once and for all.
- Had Kingdom of the Sun been made, Supai would have become the second Disney villain to be a god of death, following Hades from Hercules.