Old Kai is one of the last major characters introduced in the anime Dragon Ball Z. He comes off as a surprise, as he has not been seen in eons, because he was stuck inside the Z Sword.

He is apparently the ancestor of Supreme Kai, and he definitely looks like he is his genetic source, because they look so similar. And then we find out that the only reason he looks old is because a witch had stolen one of his Potara earrings, and that created a permanent fusion. This is the only fusion that was mixed gender, which raises some questions about Old Kai that are perhaps better left unasked.

But his personality reminds me so much of Master Roshi, as he is just kind of a dirty old man, but with the body and status of a Kai. This makes him, in some ways, a god in the strange way Dragon Ball religion/afterlife works.

But he was pivotal in making Gohan into Ultimate Gohan by unlocking his true potential… which is something that Guru already did sorta. And to make matters worse, it actually did not do anything, because they had to defeat Super Buu with fusion after he had absorbed Gohan in his ultimate form.

But I did like how he gave up his life to revive Goku, and still came back with the halo. Even more hilarious was Vegeta finding out what Goku promised Old Kai in exchange for giving Gohan his powers.