Babidi's Majins are a group of fighters put under a spell by Babidi, turning them into a Majin.
Going to Earth to unseal Buu, the wizard Bibidi was killed before he could complete his plans. However, he had a backup plan in a clone named Babidi. Babidi took control of several powerful fighters in order to complete his father's goals.
He first sends two human fighters, Yamu and Spopovich, to the 25th World Martial Arts Tournament to steal energy from other contestants. After receiving the energy, Babidi and his minion Pui Pui betray and kill the two fighters.
Babidi later sends Pui Pui and another Majin named Yakon to attack Goku, Gohan, Vegeta and Supreme Kai. Yakon is killed by Goku, while Pui Pui gets slain by Vegeta. However, Dabura discovers that Vegeta is vulnerable to Babidi's Majin spell as he still has evil in his heart. Babidi then casts his magic on Vegeta and turns him into a Majin.
Babidi later frees Majin Buu and incorporates him into his forces through bribing him. Vegeta attempts to sacrifice himself to destroy Buu, but it is ultimately fruitless. Babidi and Buu begin killing millions of people on Earth, at least until they are confronted by Goku. Goku fights Majin Buu and tells him that it's pathetic how Babidi controls him, causing Majin Buu to have an epiphany and kill Babidi, bringing an end to Babidi's forces.