For decades, the Hulk was a story about a man, Bruce Banner, constantly at odds with his alternate personality, the monstrous Hulk. However, for a brief period in the 1990s, things changed dramatically with the introduction of the "merged" version of the Hulk.

However, what was once believed to be the merged Hulk might not have been actually a merged Hulk after all. Learn about the truth behind the so-called "Professor Hulk."

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Obviously, for most of the Hulk's time in comics, he was split into either his human self, Bruce Banner, and then his rampaging Hulk form, he would always complain about the puny humans who would never leave him alone and how much he hated Banner. Banner, meanwhile, was doing everything he could to rid himself of his Hulk personality. However, when the Hulk debuted, his personality was not that of a rampaging simpleton, but rather of a crafty being who was gray.

Years later, during his run on Incredible Hulk, John Byrne re-introduced this version of the Hulk. That was the Hulk that was starring in the book when Peter David took over writing the series. David changed the status quo during his run by letting the gray version of the Hulk take over and eliminate Banner entirely, as the gray Hulk went to work in Las Vegas as a mob enforcer...

Eventually, though, first Bruce Banner returned and then so, too, did the savage green version of Hulk. They were now, in effect, competing for control of their shared body.

This led to the historic Incredible Hulk #377 by Peter David, Dale Keown and Bob McLeod. In that story, Doctor Leonard Samson used hypnosis to talk to the two sides of the Hulk, the gray Hulk and the green Hulk...

As Samson proceeded, we see that we're talking about some serious repressed rage here, going back to when Banner's father abused his mother, even going so far as to KILLING Banner's mom...

In the end, though, Banner and his Hulk personalities come to terms with their issues, and merge into one Hulk...

That, then, became the status quo for pretty much the rest of Peter David's run. Here, then, the issue was not so much that Banner could not keep himself from turning into the Hulk, but rather that Banner was worried that a merged Hulk was more dangerous, in a sense, because the Hulk with Banner's intellect could possibly be more of a danger if he ever turned evil and that's precisely the fear that Bruce had to face when he was taken to the future in the classic miniseries, Hulk: Future Imperfect (by Peter David and George Perez).

There, he met his older self, calling himself the Maestro and Bruce realized that the biggest threat to the world was, well, HIM.

Not the rampaging Hulk. Not the crafty Gray Hulk. HIM.

That was the key conflict in the rest of David's run, trying to control things to avoid becoming the Maestro. There were diversions all over the place, of course, but that was the central conflict. Of course, though, like all things, David's epic run had to eventually come to an end after over 120 issues of amazing stories.

Naturally, incoming writers had their own take on the character and after a short stint by Joe Casey, John Byrne and Ron Garney re-launched the series with the book going back to the more traditional Banner/Hulk conflict. When that run finished, Paul Jenkins took over writing duties (with Garney remaining as the artist) and Jenkins had a whole other take on the Hulk's "merged" personality.

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In Hulk #12, Jenkins (with Garney and inker Sal Buscema) had Banner revisit his own subconscious for the first time since Incredible Hulk #377 (with the help of an old girlfriend, neuropsychiatrist Angela Lipscombe) and he saw the three dominant personalities...

In the next issue, he cuts a deal with the gray Hulk that he will give him control of the Hulk body at nights so long as he allows the merged Hulk to be freed...

So that seemed like it was a pretty clear-cut change, right? The merged Hulk and the old gray Hulk cut a deal to prevent a fourth, darker personality, from controlling the body. That was a reasonable twist on the previous status quo. That, though, was not where Jenkins stopped.

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In Incredible Hulk #16 (by Jenkins, Garney and Buscema), Dr. Samson visits Angela and the merged Hulk...

Angela then presses Samson, who confesses that the Hulks never merged, he just created a THIRD, more controllable personality, the so-called "Professor" Hulk...

Professor Hulk, of course, had been the fan nickname for the merged version of the Hulk, only now it was actually made canon. As you might imagine, once you establish that something like the "merged" Hulk is actually just a tertiary personality, it makes it a lot less interesting for other writers to spotlight (if you had a choice of three different personalities, why pick the least famous of the three?) and later writers have generally gone their own route with their takes on the Hulk's personality, and the David "merged" version of the Hulk has not been seen since.

The closest we have come to seeing him was in the form of "Doc Green," which was a result of Bruce Banner nearly being assassinated and Tony Stark saving his life by putting some Extremis into his brain (Extremis was the experimental nanotechnology that Iron Man had used to recreate his armor as an almost living extension of himself) and this had caused the Hulk to become extremely intelligent again.

However, guess what, this new personality also almost turned into the Maestro!

"Doc Green" turned out to be a temporary personality change and eventually he turned back to the classic version of the Hulk. That seems to be the fate of any dramatic change to the Hulk, really. It always goes back to "classic" Hulk eventually.