The strongest human on earth!
Krillin has been Goku's best friend since they studied martial arts together under Master Roshi as kids. Krillin provides comic relief in tense situations as he tries to keep up with Goku and some of the other more powerful warriors. But don't get the idea that he's a helpless buffoon. A good fighter on his own accord, he's always there to help Goku. He can and has saved his friend's life more than once. In fact, Krillin unleashes an incredibly powerful energy blast shaped like a flying disc that literally slices through mountaintops.
Krillin is incredibly dedicated to his friends, especially Goku, and holds friendship in high value. He is willing to fight against the Saibamen and Saiyans even though he doesn't want to die. Goku encourages Krillin to have confidence in his own abilities as Krillin learns to be a remarkable fighter -- that is, for an Earthling.
Krillin volunteers to be one of the crew going to Namek to gather the Namekian Dragon Balls. On this journey he once again gets to prove his loyalty, courage, and fighting skills. His power is enhanced even further by the eldest Namekian, Guru, when he awakens the sleeping power within Krillin. He will need every ounce of this power he has to fight against the evil forces assembled on Namek.