Kamehameha
Means something like Turtle Ball Energy Blast, it was created by Kamesennin Mutenroshi (Master Roshi). Took him 50 years to learn it, and when Goku first saw it back in Dragon Ball, he picked it up in an instant. Not as good at first, but it has since then become his favorite energy attack, used many, many times throughout the 3 Dragon Ball series. And Goku isn't the only one that knows it, others include Gohan, Goten, Pan, Cell, and Ubuu (or he does something similar), oh and Chii Shinlon when he absorbed Pan. That's for used in GT, for not GT, there's also Krillen, Yamcha, Tenshinhan (Tien), Buu, Trunks (in movie 11), and Roshi of course.
Description
Cups hands by one's side, then build up a ball of energy, then releases it in front in a form of a beam.
First Used in GT: Episode 1