Goku's Saiyan name, the main protagonist in the dragonball anime. He is referred to as Kakarot by other Saiyans like Vegeta due to their saiyan heritage. However, all of his friends on earth call him Goku.
Kakarrot (or Kakarotto) are alternate spellings of his name, and all three of them can be used interchangeably. Vegeta is his arch rival, and strives to become stronger him at every turn.
Kakarrot is a fierce warrior, after he receives proper mental and physical training, he has virtually unlimited potential and is the strongest fighter in the universe.