The original legend of the Super Saiyan was more about his power than the Saiyan himself, stating that he had achieved a level of power so overwhelming that it could only be maintained in a transformed state. When the anime episode was released, a filler scene in the episode "Goku's New Power" was added showing the Super Saiyan as a Great Ape with yellowish colored fur instead of the standard brown.
The Super Saiyan was fabled to have been destroyed by his own power, and the filler visual in the anime suggests that his power destroyed the planet that he was on. In the series, the form was believed to be a myth, until Vegeta began to suspect that Goku was a Super Saiyan after seeing his drastic increase in power in a short period of time. Vegeta's suspicions are not confirmed until later, when Goku transforms against Frieza, and states that he was a Super Saiyan.