Bojack

Bojack is a space pirate of immense power who was sealed away on King Kai's planet by the four Kais acting in cooperation — the only time such joint action was required to contain a single threat. He was accidentally freed when Goku's self-destruction on King Kai's planet during the Cell Games destroyed the planet and released Bojack. Appearing on Earth during a martial arts tournament, he nearly killed Gohan until a spiritual boost from Goku's ghost broke through Bojack's aura, allowing Gohan to defeat him with a Kamehameha.