Since Avengers: Endgame closed the story on several of Earth's Mightiest Heroes, there's been one Avenger whose future still remains in the dark. His cousin, the Sensational She-Hulk, may be getting her own Disney + show, but the next moves of Bruce Banner and the Incredible Hulk have not appeared in any of Marvel Studios' many announcements for upcoming films or shows. With his hero days seemingly behind him, many have speculated that the Hulk's next major role could be as a villain, whether in an adaptation of World War Hulk or as a version of his future self, the Maestro.
For years, the Hulk remained as the big, angry muscle of the Avengers. But It wasn't until Thor: Ragnarok that the MCU really capitalized on the struggle for control that was always raging between Bruce and his green alter-ego. Catching up with the Hulk on Sakaar, the Hulk's resentment and anger towards Earth became much clearer in his time as a gladiatorial celebrity. Looking back on the 2017 film, besides beginning the path towards his current status as Professor Hulk, a closer inspection may reveal that the film also began to address one of the Hulk's most horrifying aspects and tease the greatest threat to the MCU.
Before the climactic battle, Bruce is faced with the choice to risk his recent freedom by transforming into the Hulk to battle Fenris, the Asgardian wolf that served Hela, and save the Asgardians. Replicating a move from his 2008 solo film, Bruce drops from their ship to transform before hitting the ground. This time, however, Bruce smashes into the Rainbow Bridge and lies broken on the ground. Although a quick comedic beat, it's evident that Bruce is gravely injured, most likely dead, from the fall. Yet, a few moments later, the Hulk has woken up and is ready for battle. At this moment, the movie revealed a glimpse of the Immortal Hulk.
The Immortal Hulk moniker came after the realization that Bruce Banner could not remain dead, after a quick series of deaths and subsequent resurrections. Whether shot, dismembered or dissolved, nothing could keep the Hulk down as he would make a vengeful return. Besides Bruce, the Hulk has also reformed his body after it was cut into pieces and stored in jars. With these regenerative powers fully in the open, there has been almost nothing that could stop the Immortal Hulk's path of destruction, including one of the most powerful iterations of the Avengers.
This ability has already been hinted in previous MCU films. As Bruce confessed in 2012's The Avengers, at his lowest point, he shot himself in the head only for the Hulk to spit the bullet out. Given the fact that the Hulk could never have transformed in time to prevent the bullet from entering Bruce's head, it isn't hard to imagine that the Hulk would have needed to heal Banner's fatal wound after transforming. In these moments, if they were to be seen, the Hulk's transformation would bear a striking similarity to his Immortal counterpart, whose flesh morphs to heal any wounds.
The emergence of this version of the Hulk also holds a great threat to the MCU, when one considers the Immortal Hulk's true name: the Devil Hulk. This persona of the Hulk's greatest desire is not to save the world or be left alone, but to end the world around him. Already, the Hulk has expressed his frustrations with the world of humans that surrounds him. If these frustrations continued, the Hulk could soon make the choice to rid himself of the nuisance. Another important element of the Hulk is that he can only come out at night, which is his time. While fans have seen moments of the Immortal Hulk, this would explain why we have yet to see any true appearance of the Devil Hulk.
In the distant future of the Marvel universe, the Devil Hulk's final transformation came when he consumed Franklin Richards and became the Breaker of Worlds. With this new power, the Hulk became a Galactus-level threat and went on to destroy whole galaxies. Already, the Hulk of the MCU has come into a similar power source when he wielded the Nano Gauntlet with the Infinity Stones. Even though he used the power to save everyone, the Hulk's hidden personality could have also saved some of that power for himself. If the Devil Hulk lurks in the mind of Bruce Banner, he would never waste the opportunity for the destruction that came with that moment.
As the capabilities of the Immortal Hulk emerge in the MCU, the Devil Hulk can't be that far behind. As an original Avenger that is much more trusted in this world, a Hulk that wants to destroy the world would be a massive threat to the many heroes that will be appearing in the future. With his power, there's almost nothing that could contain his unkillable rage.