In the past,when Goku and Krilin were just kids,they were rivals,but they became good friends.Krilin is human but he can control his energy.He is always bald and he grew hair after he began to live with Android 18.Goku is much stronger than him,but he is always ready to help as he can.Krilin helped to fight the saiyans,but Nappa was just too strong for the earthlings.Gohan and Krilin survived this battle,thanks to Goku.After that,he and Gohan fought Vegeta and Krilin was about to kill him,when Goku asked him to let Vegeta go away.After this,he and Gohan and Bulma went to Namek to collect the dragon balls,where they faced the strongest warriors in the universe:Ginyu force,Frieza and more...When Goku hit Frieza with a Spirit Bomb,he was so angry that he killed Krilin.Goku's rage at Frieza turned him to Super Saiyan.In Cell sagas,he didn't used the tool that was design to destroy Android 18,because he loved her.Cell absorbed her,and after Gohan defeated him,he spitted her out and Krilin asked the dragon balls to remove the bomb which was inside her body.After 7 years,they began to live together,and they have a daughter named Marron.Krilin is a very good person,and he is always ready to help as he can.