Kid Buu is the original and purest form of Majin Buu. Unlike his other forms, this form of Buu's thought process is seen to be irrational and spontaneous, even destroying his own body to destroy the Earth. Although he appears smaller than any other form, he is more dangerous than any other forms of Buu due to his full relentless evil and unpredictability. He is also completely free of restraint and has no trace of sanity and, because of this, is extremely volatile. He retains his childish personality, becoming amused and laughing hysterically at his own destruction of entire worlds. He fought against Goku and Vegeta in the Sacred World of the Kais and was finally defeated for good by Goku's Super Spirit Bomb powered by the energy of every person on the newly revived planet Earth.