After the great cataclysm and drought on Namek, Guru was one of two survivors of the race (the other being the Nameless Namekian who would become Kami and King Piccolo). Guru would repopulate the race of Namekians himself, being every Namekian's father. He would serve as their beloved Grand Elder.
Guru is the creator of the Namekian Dragon Balls and the eternal dragon Porunga.
When Frieza attacked Namek looking for the Dragon Balls, Guru amplified the hidden powers in Krillin, Gohan and Dende. The grief of having lost all his children caused him to die prematurely. In a gambit by King Kai, it was arranged for the Earth dragon Shenron to restore the lives of the Namekians Frieza killed. When this happened, Guru was revived.
Guru and the other Namekians were wished to Earth to be saved from Namek's destruction. Before he passed a natural death, he made Elder Moori the Grand Elder of the Namekians.