Lacking the direct involvement of Dragon Ball creator Akira Toriyama and facing mixed fan reception upon its initial release, the status of Dragon Ball GT has been the subject of healthy debate among fans in the decades since the anime series' conclusion. One of the most popular additions to the larger Dragon Ball franchise in the series was a new Saiyan transformation, Super Saiyan 4, which appeared prominently for the series' second half.
With the most recent anime series Dragon Ball Super further distancing itself away from GT, we're taking a closer look at the fan-favorite transformation's history to see if it is still regarded as canon and unpack the hints from Super that it may still be possible to achieve.
What Is Super Saiyan 4?
As Goku battled GT's first major antagonist, Baby, possessing the body of Vegeta and augmenting it with Tfuffle technology, he found himself hopelessly outmatched, even at Super Saiyan 3. Moments before being obliterated by Baby's ultimate attack, Goku was rescued by the Supreme Kai and transported to their heavenly world. The Elder Kai revealed that if Goku could regrow his tail, he could achieve his full Saiyan potential and, after a painful process, Goku's long-lost tail reappeared.
Goku returned to the alternate Earth created by Baby with the Black Star Dragon Balls to engage the villain in a rematch but was quickly defeated once again. Beaten within an inch of his life, Goku stared at the Earth and -- just as the full moon affected Saiyans with intact tails -- the sight of his adopted home planet caused him to transform into a giant ape. However, given Goku's Super Saiyan potential, the ape was covered in brilliant golden fur. Goku's granddaughter Pan calmed down the rampaging golden ape, with Goku transforming back into his adult humanoid form in a new state covered in red fur and long, black hair referred to by the Elder Kai as Super Saiyan 4.
Super Saiyan 4 in Dragon Ball GT and Dragon Ball Heroes
As a Super Saiyan 4, Goku is able to eventually overpower Baby and force him to leave Vegeta's body, before completely destroying the villain with x10 Kamehameha Wave. Now able to transform into the powerful state without the need of gazing upon the Earth, Super Saiyan 4 allows Goku to return to an adult form after being reverted into a child by the Black Star Dragon Balls. Vegeta later gains the ability to transform into a Super Saiyan 4 after being doused in energy from a device invented by his wife Bulma, with the two old friends fusing into the composite warrior Gogeta to become a Super Saiyan 4 during the climactic battle against Omega Shenron at the end of GT.
As staple in video games following the conclusion of GT, the Japanese arcade game Dragon Ball Heroes would expand the characters that could unlock the form. The Legendary Super Saiyan Broly would gain access to Super Saiyan 4 along with Gohan, Bardock and Vegito. There were plans for Trunks to similarly be able to transform into a Super Saiyan 4 in the game but these plans were scrapped when the developers were unsure of what color to have the transformed Saiyan's fur.
Dragon Ball Super: Broly
While the events of GT were largely retconned by the latest anime series Dragon Ball Super, the animated film Dragon Ball Super: Broly reimagined its eponymous antagonist with a state that resembled Super Saiyan 4's feral origins. As Broly became enraged while fighting against Goku and Vegeta, he entered something referred to by his father Paragus as a "wrath state."
According to Paragus, the wrath state allowed Broly to harness all the raw, rapidly escalating power of a Saiyan in their great ape form while retaining their humanoid appearance -- at the expense of all semblance of self-control. As Broly's rage increased, he found himself more than a match for Goku and Vegeta, even while the duo were transformed into Super Saiyan Blue, forcing them to fuse into Super Saiyan Blue Gogeta and defeat him once and for all. Although this doesn't bring Super Saiyan 4 into canon, it lays a very solid foundation for the transformation on a conceptual level.