Dragon Ball Z has several heroes both big and small, and that was definitely the case with the "Buu Saga." With even a joke of a character like Hercule being pivotal in the series' ultimate story arc, it was all hands on deck to ensure that the world made it out okay. Unfortunately, one of the franchise's characters never really gets his due, despite how important he was in undoing all the damage that Buu unleashed.
Formerly Kami's loyal assistant, Mr. Popo later throws Dende, Kami's replacement, to safety. This not only preserves Dende's life but allows the remaining Z Fighters to wish everyone who had died back to life. This quick thinking might not rate in regard to flashy special attacks, but it does cement Mr. Popo as one of the best and most necessary Dragon Ball Z characters ever.
Mr. Popo Saved Dende's Life Against Majin Buu
Mr. Popo and others upon the Lookout observe the fight between Piccolo, Gotenks and Majin Buu. Gotenks had been one of the Z Fighters' last hope against the evil creature, but both he and Piccolo are finally defeated and absorbed into Buu's being. From there, Majin Buu becomes Super Buu, finding the location of the Lookout and launching an incredibly powerful attack. Literally called the Human Extinction Attack, this move, as its name implies, kills pretty much everyone on Earth.
Some of the few survivors include Hercule and Dende, with the latter being due to Mr. Popo's ingenuity. Seeing what Buu was planning, Popo grabbed and threw Dende off the Lookout and away from danger. As the others are rendered into chocolate for Buu's consumption, Dende makes it away alive. He helps his old friend Gohan by healing him to go and fight Buu, and though Gohan is later absorbed as well, this stalls for time until both Goku and Vegeta could come back to life to take Buu on. However, this wasn't the only way that Dende ultimately turned the tide.
Mr. Popo's Quick-Thinking Helped Grant DBZ's Last Wish
Toward the climax of the "Buu Saga," the restoration of Earth and its people remains a huge worry, especially with Buu's rampage still ongoing. Dende helps to lighten the mood, however, by remembering that everything can be restored by wishing for it with the Namekian Dragon Balls. This comes to pass after Buu is defeated, but it wouldn't be possible without Dende. At the same time, the young Namekian wouldn't have survived himself without Mr. Popo.
Mr. Popo never did that much throughout the Dragon Ball franchise, being more of a side character than even the likes of Tien or Yamcha. However, the chain of events he set off by throwing Dende out of Buu's path was ultimately the deciding factor in beating the villain and reversing his massacre. After all, Dende needed to heal Gohan to hold Buu at bay for a while, and he was likewise necessary to translate Vegeta's wish to have everyone that Buu killed brought back. This says a lot about both Dende and Mr. Popo's usefulness, with Kami's former assistant being perhaps the true hero of the "Buu Saga."