Dragon Ball Z - Episode 2 1/2

Goku and Gohan arrive at Master Roshi's island to meet Bulma, Krillin, Master Roshi, and Turtle. As the old friends catch up, the same mysterious alien arrives at the island and reveals himself: he is a Saiyan warrior named Raditz, and he is Goku's older brother. He also reveals that Goku's real Saiyan name is Kakarrot. Goku learns that he was sent to destroy all life on Earth, but his memory loss from a terrible fall as a child prevented this outcome. Raditz came to Earth to get Goku to join him and the other two remaining Saiyans, and he won't accept a refusal.