A form of Super Saiyan that originally appeared in the anime-only Dragon Ball GT. Born from gaining control over the Golden Oozaru form, its main features are red fur covering the torso, longer hair, red lining around the eyes, and the addition of a monkey tail even if the user already had them cut beforehand.
Son Goku is the first to achieve this form, followed by Vegeta and their fusion, Gogeta (whose Super Saiyan 4 form is different from his fusees, since his hair turns red and his body gains brown fur instead). It can be upgraded into Super Full Power Saiyan 4.
The form would be canonized with its appearance in Dragon Ball DAIMA, though appearance-wise it would see some changes, such as rendering the hair in the same color as the fur, and the arms and hands getting proportionally larger per GT's original concepts.
