Goku’s fight against Majin Vegeta in the ''Majin Buu'' arc is one of Dragon Ball Z’s most iconic clashes. Vegeta, having been possessed by the warlock Babidi, goads Goku into having a rematch with him by slaughtering hundreds of innocent bystanders at the World Martial Arts Tournament.
An enraged Goku decides to fight Vegeta, knowing full well that any blow he deals to the Saiyan Prince will accelerate Majin Buu’s impending reawakening. Before the two fight, however, the Supreme Kai interjects, standing between them as he warns Goku that fighting Vegeta will awaken Buu. In response, Goku silently charges up a ki blast, and the Supreme Kai reluctantly backs down, letting Goku fight Vegeta in spite of the consequences.
Was Goku Going to Kill Supreme Kai?
It's an immensely shocking moment that begs the question: did Goku intend to go through with killing the Supreme Kai? Many Dragon Ball fans believe the answer to be yes and point to the fact that while Goku generally values life, he has been shown to believe that -- depending on the circumstances -- one’s life is worth sacrificing to save another’s.
For example, when Cell nearly kills Piccolo, Goku stops Gohan from saving him, rationalizing there’s no point in his son throwing his life away. In that moment at the World Tournament, it’s possible Goku was conveying to the Supreme Kai that his life is worth trading for the thousands more Vegeta might kill if left unchecked.
It’s also worth mentioning that the Supreme Kai possesses telepathy, and would have been able to read Goku’s mind. Given how shocked the Supreme Kai is by Goku’s threat, it’s entirely possible he had done this and sensed the Saiyan's killing intent, resulting in the deity backing down.
Goku Could Have Just Knocked Supreme Kai Out
Despite the scene effectively selling the severity of the moment, many find it unlikely that Goku would have gone through with killing the Supreme Kai. Goku’s attitude toward life is so sacrosanct that he even makes a point of trying to spare villains, and it’s unlikely that he would outright commit cold-blooded murder.
What’s more, Goku’s threat to the Supreme Kai may not have entailed killing him. His blast could have easily just incapacitated him or sent him flying, which would still be an extreme stance for Goku to take without betraying his core ideals. This reading of the scene doesn’t undermine its dramatic weight, but nor does it contradict Goku’s past actions as a steadfast protector of life. What makes it even more compelling is another question: was Goku right to challenge Vegeta in the first place, and what was his motivation to do so?
Given his past attitudes, it’s likely that protecting innocents was at least part of the reason why Goku was adamant about fighting Vegeta. However, Goku also enjoys a good fight and had already expressed excitement about getting to fight Vegeta in the tournament. Said tournament getting derailed is what led to Vegeta taking drastic action to ensure they fought at all, and while Goku wouldn’t approve of Vegeta’s methods, it’s hard to say whether he’s outright against getting to battle him in the first place.
Goku Did What He Felt Was Best in Fighting Vegeta
What’s more, Goku has the ability to use Super Saiyan 3 the entire time, but doesn’t transform at all during his fight against Vegeta. When Vegeta takes Goku to task on this later in the arc, Goku retorts that using Super Saiyan 3 while undead drains time in the mortal realm that he couldn’t afford to lose.
Despite this, Goku used the form against Majin Buu when the stakes were much higher, and him suddenly disappearing would have had disastrous consequences. The true intent behind Goku’s actions here has been the subject of intense debate, but it’s entirely possible that he chose to fight Vegeta on equal ground as Super Saiyan 2s, and going SS3 would have cut too much of his remaining time on Earth for their rematch.
The true answers to these questions will likely never receive official answers, but that only adds to the weight of the moment. Despite frequently being dismissed as a simple hero, Goku is a deeply multi-faceted character, and his actions are often open to interpretation. Whichever way it can be interpreted, his threat to the Supreme Kai stands as one of his most morally grey actions in Dragon Ball Z, and has kept fans coming back to debate it countless times over the years.