Vegetto was formed during the Buu Saga when Vegeta and Goku fused together with the Potara earings. This causes them to fuse forever. Vegetto is eaten by Buu and split back into Vegeta and Goku. They later are given the chance to fuse again but decide not to and destroy the earings. Goku later beats Buu by himself. Vegetto is thought to be the most powerful being.
