While Akira Toriyama's enormously popular Dragon Ball franchise has certainly leaned into tragedy and defeat before, one of the most tragic characters across the manga and anime series is one of the story's most common sources of comic relief: King Kai. A friend and cosmic martial arts mentor to Goku and several of the Z Fighters, King Kai's life has been nothing but one setback and hardship after another ever since Goku first arrived at his home at the start of Dragon Ball Z.
While King Kai remains cheerful as ever, though visibly annoyed at what's become his life, these developments underscore his long-suffering character arc right through the current manga/anime story in Dragon Ball Super.
King Kai is responsible for overseeing the North Galaxy -- the quadrant of Universe 7 where Earth is -- maintaining his divine duties from his home on a small planetoid at the end of Snake Way in the afterlife. King Yemma directs Goku to King Kai's planet for training in DBZ following his death at the start of the series to prepare for the arrival of the Saiyans. Setting the tone for his character, King Kai agrees to train Goku, but only if he can overcome a pair of trials and tell a joke funny enough to make him laugh.
Goku accomplishes the trials and, with King Kai's guidance, learns the Kaioken technique and Spirit Bomb. The Saiyan fighter then returns to Earth, though King Kai would continue to advise him from his home telepathically while training some of the other Z Fighters.
The real tragedy for King Kai strikes approximately halfway through DBZ during the Cell Games. As Cell prepares to self-destruct and obliterate the Earth, a desperate Goku teleports himself and Cell to King Kai's planet with seconds to spare, reasoning that this would significantly minimize casualties. Unfortunately, the resulting blast killed Goku, King Kai, and Bubbles and Gregory -- Kai's constant companions -- while his planet was utterly obliterated. While the group was allowed to keep their bodies in the afterlife, King Kai was ridiculed by his fellow Kais for being dead as he was forced to rebuild his home in the aftermath.
Even after the Elder Kai resurrected Goku at the end of DBZ, King Kai and his companions were still dead by the start of Dragon Ball Super. When Goku decided to intrude and train on his rebuilt planet, King Kai scolded Goku for forgetting about this detail. Goku vowed to use the Dragon Balls to resurrect King Kai and his companions when he returned to Earth.
However, after the arrival of Beerus, the God of Destruction wrecked King Kai's planet yet again during his fight with Goku. Once again, Goku had forgotten about his promise, frustrating King Kai to no end. And as Dragon Ball Super has continued in the manga beyond the events of the anime series, King Kai's wish to gain a bigger planet and finally live in greater comfort was thwarted by Goku once more. He wishes for a world the size of King Kai's original one, leaving him exactly where he started thanks to Goku's usual ignorance.
While all these hardships and frustrations are certainly played for laughs, making King Kai the recurring butt of jokes, the North Galaxy ruler has had a rough life ever since Goku entered it. He constantly has to rebuild and clean up his home from Goku's unexpected arrivals to train and deal with opponents like Cell and Beerus. Plus, he's been killed and repeatedly forgotten while other longtime characters are brought back to life. King Kai just wants to be brought back to life and given a chance to improve his celestial standing a marginal bit, only to be perpetually let down.