The Super Saiyans
Goku:
One of the two full blooded Saiyans and the main character of Dragonball/Z/GT who was sent to Earth as a baby. He's not very bright, but very kind. He will do anything for his friends and those feelings help him become a stronger person. In fact, it was because of the death of his friend Krillen that triggered his change into a Super Saiyan.
Vegeta:
Vegeta is also a full blooded Saiyan who doesn't seem to be a people person. In fact, he was one of the villians of Dragonball Z until the death of Frieza. He has a very strong ambition to be stronger than Goku which triggers his change to become a Super Saiyan.
Gohan:
Gohan is the child of Chi Chi and Goku. With the strict rules of his mother, he is very bright and a hard worker. With the kind heart of his father, he is one of the strongest characters in Dragonball Z. Gohan demonstrates a sort of hidden power within himself that helps in his change to a Super Saiyan.
Trunks:
Trunks is a very interesting character. He's the child of Bulma and Vegeta. He first appears in the battle with Cell as a time traveller from the future and warns Goku and the others about Dr. Gero's androids. This Trunks turned into a Super Saiyan after the death of his master, Gohan.
Trunks then makes another appearance as the child of Bulma and Vegeta in the present. He's best friends with Goten, Gohan's younger brother. Trunks becomes a Super Saiyan at the age of 8 though what triggered his change is unknown.
Goten:
Goten is a very powerful character and best friends with Trunks. He changed into a Super Saiyan at the age of 7 when training with his mom. Goten looks just like Goku when he was young (minus the tail) and has the same care-free personality. He fuses with Trunks to become Gotenks.
