When Goku traveled to the afterlife after the Cell Games, he was introduced to the other Kais from different parts of the galaxy. The anime had a filler arc that was set in the afterlife, where fighters from across the universe battled in a tournament in order for a chance
to be trained by the Grand Kai.
The Grand Kai was the ruler of the other Kais and was said to be one of the strongest warriors in the universe. He also looks like a guy who follows the Grateful Dead around on tour.
You might think that Grand Kai doesn't belong on this list, due to him being a character created for the filler arcs. His inclusion to the story was actually suggested by Akira Toriyama.
The presence of the Grand Kai was mostly made redundant by the arrival of the Supreme Kai in the Majin Buu arc, as he fulfilled much of the same role. The pantheon of the universe grew much larger in Dragon Ball Super and the gods have taken on a much larger role in the story, yet we still haven't heard anything from the Grand Kai in a long time.