1. Gray Hulk - “The Incredible Hulk”
More intelligent than his green counterpart, the Gray Hulk went by the pseudonym of “Joe Fixit” and took up residence in Las Vegas working for a crooked casino owner. Banner, repressed in Hulk’s mind, eventually reasserted himself until they began to change places with each sunrise and sunset, with Hulk asserting himself at night.
2. The Incredible Thing - “Age of Apocalypse”
In an alternate reality where Bruce Banner never became Hulk and mutants rule the world, the human Banner was a member of the Human High Council, the ruling body of the surviving human population.
However, he longed to become a mutant in order to escape being a second-class citizen. Caving in to the moral low ground, Banner sold himself to one of the Horsemen of Apocalypse in order to experiment on mutants and eventually himself. The results were the Thing, a Gray Hulk variant Banner could revert between at will.
3. Aboriginal Hulk - “House of M”
To control his dark side, Bruce Banner goes into seclusion. Setting up shop among the Aborigines of Australia, they help him achieve peace with himself by detaching from society — until the new totalitarian mutant government threatens the safety of his new friends. Then all bets are off as Hulk teams up with terrorist group A.I.M. to conquer all of Australia.
This story is the lead-up to the much lauded Civil War series.
4. Infernal Hulk - “The Incredible Hulk”
In a reality where Bruce Banner and Hulk were separated into two bodies by magic, Hulk ended up being cast into hell. Corrupted by the demonic beings he encountered eventually converted Hulk into a demon. Devoid of any sense of good, Infernal Hulk escaped from hell and attempted to kill his creator, Bruce Banner.
5. Skulk - “Amalgam Comics”
The Amalgam universe was a publishing mash-up between comic book powerhouses Marvel and DC. Literally. Each publication took different heroes and merged them with characters from the other.
Skulk is what happened when Bruce Banner was running tests on a gamma bomb in the desert and Solomon Grundy showed up. The bomb exploded, accidentally fusing the two, so when Banner became angry, he turned into Grundy. Skulk is the name the creature deemed itself with.
6. Maestro - “Future Imperfect”
One hundred years in the future of the current Marvel universe, nuclear war laid waste to much of the world’s population, both human and superhuman. Driven insane by the radiation, Hulk morphs into the tyrant Maestro.
With the intelligence of Bruce Banner and the malevolence of a man bitter by his lot in life, Maestro rules the world with an iron fist until he is defeated by a time-traveling “modern day” version of himself.
7. Zombie Hulk - “Marvel Zombies: Dead Days”
Infected by the zombie Fantastic Four, the virus negatively impacts Hulk’s regenerative powers. He retained his strength and invulnerability and gained a craving for human flesh, which triggers his transformation from zombie Bruce Banner to zombie Hulk. In Hulk form he gorges to the point where his stomach partially bursts when he reverts back to his human shape.
8. Old Man Hulk - “Hulk: The End”
Alone in the last days of Earth, Hulk and Bruce Banner wander the ruins left by nuclear holocaust as two defined personalities sharing one body.
The only remaining human on Earth, Banner takes it upon himself to record a video log of being the last of his species and slowly descends into suicidal depression, though his regenerative powers keep him from being able to follow through. His Hulk personality, meanwhile, clings to life, fighting off the mutated animals and forging ahead despite the hopelessness of it all.