North Kaio

King Kai (界王 Kaiô, literally, King of the Worlds) or North Kai (北の界王 Kita no Kaiô, literally, King of the Worlds of the North) is a Hero in Dragon Ball Z and Goku's final martial arts teacher, and later mentor. He also taught Piccolo, Tien Shinhan Yamcha, and Chiaotzu. His planet is at the end of a long winding road known as Snake Way, where he teaches powerful, new techniques such as the Spirit Bomb and Kaio- Ken. Despite the fact that his planet is around 100 feet in diameter, its gravity is ten times greater than Earth's. He has a monkey named Bubbles and a motor-mouth grasshopper named Gregory

Saiyan Saga
King Kai first meets Goku when Goku journys to King Kais planet to seek his traning King Kai teaches Goku the Kao Ken attack which doubles the users power and a red auroa which surroneds them.

Frieza Saga
During the Frieza Saga King Kai trains Piccolo Tien Shinhan Chiaotzu Yamcha.

Androids and Cell Saga
Before the Cell games Goku teleported to King Kai's place to get a better sensing range so he'd find a new guardian for the Earth. Later during the Cell games when Cell is fighting Gohan and is caused to revert into his "imperfect" form, Cell decides to take the Earth with him and tries to blow up. Goku makes a last second desicion and teleports him to King Kai's planet where he explodes, destroys the planet and kills Goku, King Kai, Gregory and Bubbles.

Students

 * Goku
 * Piccolo
 * Tien Shinhan
 * Chiaotzu
 * Yamcha
 * Olibu
 * Majirone
 * Many others Aliens