Goku has saved Earth more than once.
Vegeta has fought gods.
Gohan defeated Cell.
But ask the average person in the Dragon Ball universe who Earth's greatest hero is and there's a pretty good chance they'll tell you:
MR. SATAN!
Known as Hercule in several English adaptations, Mr. Satan is Earth's celebrity martial-arts champion, professional showman, world-class self-promoter, and a man who has somehow built a heroic reputation on being standing somewhere nearby when considerably stronger people saved civilization.
To be fair...
He is legitimately tough.
By normal human standards, Mr. Satan is an accomplished martial artist with impressive strength and fighting ability.
Dragon Ball stopped operating by normal human standards approximately seventeen explosions ago.
Faced with Super Saiyans, androids, energy blasts, flying warriors, and monsters capable of destroying planets, Mr. Satan responds with one of his most reliable techniques:
Insisting it's all a trick.
His outrageous boasts and habit of taking credit for other people's victories make him one of Dragon Ball's great comic frauds. The world believes he defeated Cell, and Mr. Satan is not exactly racing toward a microphone to correct the record.
But writing him off as a useless coward misses what makes the Character special.
Because when Majin Buu enters his life, something remarkable happens.
Mr. Satan initially approaches Buu with plans involving deception rather than anything resembling a fair fight. Instead, he gets to know him. Their relationship becomes genuine, and Mr. Satan's kindness helps draw out Buu's capacity for friendship and compassion.
For once, the great champion isn't pretending to accomplish something important.
He actually does.
Later, when Goku desperately needs the people of Earth to contribute energy to defeat Kid Buu, the mighty warriors struggle to convince humanity to listen.
Mr. Satan speaks.
The world listens.
That's the wonderful joke at the center of the Character. Mr. Satan's celebrity is built on exaggeration, misunderstanding, and shameless self-promotion...
But eventually the ridiculous reputation becomes something the real heroes actually need.
He's a fraud.
He's a coward.
He's a loving father and grandfather.
He's a genuine friend.
He's occasionally brave despite being absolutely terrified.
And against all reasonable expectations...
Mr. Satan really does help save the world.
Just don't ask him to explain exactly how.