From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
A Kaioshin would be born when the Kaiju grew incredibly rare golden fruit. Unlike the normal Shins, who could later possibly become normal Kaio, the Shins born from the special golden fruit had far more power and longer lifespans – up to millions of years longer than the average member of their race whose lifespans were given in the Super Exciting Guide as around 75,000 years.
Protectors of the universe
Each of the Supreme Kaios once ruled over a quadrant of the entire universe, with a Grand Supreme Kai overseeing them and who ruled over the entire universe (the same way that regular Kaios are the highest gods of their individual quadrants of a galaxy, with a Grand Kaio in charge of the four of them). Each Supreme Kaio oversaw the regular Kaios in their quadrant of the universe.
According to Supreme Kai (the Eastern Supreme Kai), each of them were a thousand times more powerful than Freeza (however, in the manga, he simply states that all could kill Freeza in a single blow), but all except for him were killed or absorbed by Kid Boo in 5 Million Before Age, resulting in the mindless killing machine seen in the first two forms of Buu being "tamed" into becoming the innocuous fat Majin Boo first shown in the series.
Like the regular Kaios, the Supreme Kaios are among the few living residents in the Other World. They can still die, however, since they are already in the Other World, it does not really affect them in the long run, unless they are somehow obliterated or absorbed. Unlike regular Kaios, who, like the North Kaio, had to visit King Yemma after his death in the anime, Kaios like the Elder Kai also received halos after death, but were never forced to visit the giant Ogre. This is likely due to the incredible supremacy such Kais have over the lowly Ogre in comparison.