Bojack serves as the main antagonist and leader of the Galaxy Soldiers. His name pulls from the Japanese term for "arrogance" or "audacity," which pretty much sums up his whole deal. His ambition is straightforward: conquer the universe and eliminate anyone foolish enough to get in his way.
The Kais had managed to seal him away inside a star, but that didn't last. According to North Kai, the seal cracked when Goku teleported the self-destructing Cell to his planet—a move that killed both Goku and North Kai in the blast, and conveniently freed Bojack in the process.
He's genuinely bloodthirsty, the kind of villain who casually mentions how long it's been since he last "snapped someone's neck" when he first reveals himself to Gohan. What's worse is that he shows basically zero loyalty to his own crew, which doesn't exactly inspire confidence in his leadership style.
Akira Toriyama, the original manga creator, designed Bojack and his entire team specifically for Toei's theatrical film. His character designs are documented in Daizenshuu 6.
Content compiled by AnimeList.moe from publicly available sources.