Goku is a Saiyan and the star of the Animes "Dragon Ball", "Dragon Ball Z", and "Dragon Ball: GT" No matter how many times he is killed, in the end, everyone else proves useless and he has to save the day. In fact, from day one, the writer of the Dragon Ball Manga made a rule that in the end Goku magically comes back to life (usually bending some rule that's already in place) and saves the day. He is known for his extreme transformations into a Super Saiyan, Super Saiyan 2, Super Saiyan 3, and the Over-powered Super Saiyan 4. He also is remembered by his trademark "Kamehameha" wave, and his huge appetite.
Oh, and his power level is over 9000.
"Vegeta, what does the scouter say about his (Goku's) power level?" - Nappa
"It's over 9000!!!" - Vegeta
Vegeta and Nappa's conversation in relation to Goku's rising power level.
"Goku hath power level over 9000"