Dragon Ball Z: Plan to Eradicate Saiyans

It is revealed to Goku that Raditz is his long-lost older brother and that both of them are members of the Saiyans, an almost extinct alien warrior race. Raditz travels to Earth on a spacecraft. Goku (formerly known as Kakarot) was brought by the Saiyans to Earth as a newborn to conquer the planet on their behalf. However, soon after arriving, he received a serious brain injury, which caused him to lose all memory of his mission and his bloodthirsty Saiyan nature. The only remaining Saiyan warriors are Raditz and two elites, Vegeta and Nappa, thus Raditz comes to ask Goku for assistance in conquering frontier worlds. Raditz kills Goku and Krillin in a single blow after Goku declines to join them. He then kidnaps Gohan and threatens to kill Goku if he doesn't kill 100 humans in the next 24 hours. To beat Raditz and save his son, Goku decides to link up with his arch-enemy Piccolo, who was previously defeated by Raditz in a prior confrontation. Gohan assaults Raditz to save his father throughout the fight, briefly outperforming Piccolo and Goku due to his wrath. Goku restrains Raditz at the end of the fight so that Piccolo can use the fatal Special Beam Cannon attack on them, mortally injuring both of them and killing them shortly after. Prior to dying from his wounds, Raditz tells Piccolo that the other two Saiyans are far stronger than him and will attack with the Dragon Balls in a year.