An ancient and wise master of martial arts, Roshi has accumulated great power and knowledge. He is very old, completely bald and has a long, white beard. Because he has lived for countless years on a deserted island with only a turtle for a companion, he is also called the "Hermit Turtle". His home, the Kame house, continues to serve as a gathering place for the good guys.
Although he may appear strange, frail and harmless, Master Roshi is indeed a great warrior. He originally trained Goku and Krillin when they were young boys and taught them the "Kamehameha", a power which is channeled through the hands, creating a wave of tremendous power that can destroy mountains. The first earthling to ever understand how to nurture and control the Power of Light, Roshi trained Goku and Krillin in its use.
Master Roshi also trained Ox-King (Chi-Chi's dad) and Grandpa Gohan (Goku's adoptive grandfather) years ago.