What Happened To Every Version Of The Hulk?

Created after psychiatrist Leonard Samson merged Bruce Banner's psyche with that of Savage Hulk and Grey Hulk, the Merged Hulk - who would later be renamed 'The Professor' - is the best of all three worlds, combining intelligence, strength and wit into one form.

However, it is later revealed that this not the combination of all three characters, but rather a new version of the Hulk who merely thinks that they are the product of all three consciousnesses being combined.

As such, the Professor is also with the other various alter egos within the mind of Banner - although he was retconned by writer Peter David into being a hallucination caused by Nightmare, so it's unclear if he is still considered a legitimate alter ego.