Gogeta

This is the super fighter created by the fusion of Goku and Vegeta. Fighting side-by-side, Goku and Vegeta were unable to defeat the monster Janemba. Thus, Goku somehow persuaded Vegeta to perform the Fusion Technique. The result was the birth of the ultimate warrior, Gogeta. Gogeta's appearance has characteristics inherited from both Goku and Vegeta, but his clothes change to the costume of the Metamoran alien that taught Goku the Fusion Technique. In addition to Goku and Vegeta's signature moves, Gogeta can also perform a variety of original attacks, such as the "Soul Punisher", a rainbow-colored energy blast that bursts an opponent into small pieces. Though Goku and Vegeta ultimately succeeded in their fusion, their first attempt was a failure, producing a short, fat fighter by the name of "Veku"...

In Dragon Ball GT, Gogeta can become Super Saiyan 4. At Vegeta's suggestion, he and Goku unite to battle the seemingly unstoppable Omega Shenron. Aside from his bright scarlet hair, Gogeta's characteristics are similar to that of a Super Saiyan 4: the upper half of his body is covered in [tag:420479 red fur], and he takes on a somewhat wild demeanor. He still wears his previously seen Metamoran costume. Having achieved his ultimate power, Gogeta is able to to brush Omega Shenron aside like an insect. He is a warrior without peer, and demonstrates this by performing his ultimate finishing move, the "Big Bang Kamehameha" (a combination of Goku and Vegeta's signature attacks). Invincible though he seems, Gogeta has one serious weakness. He can only exist for ten minutes at a time, the duration of the Fusion Technique.

Source: Character Reference, Dragon Ball Z: Budokai Tenkaichi 3